Bounded-Error Log

all the words we leave behind

Wed, 31 Dec 2025 19:49:40 -0800

Here I go quoting song lyrics to myself again I have to confess I almost forgot to write a year-end post until today, New Year’s Eve. What did I do in 2025? As before, I worked on a lot of things on Anthropic’s interpretability team, including our massive circuit tracing and biology papers from March. Also as before, I helped run Galactic Puzzle Hunt 2025 with the rest of ✈✈✈ Galactic Trendsetters ✈✈✈ in September.

Gold-medaling the 2025 IMO was easier than average

Wed, 03 Sep 2025 01:02:59 -0700

(Background/disclaimer: I work at Anthropic, far from any efforts related to math reasoning or evaluations; opinions are my own. I was an IMO gold medalist in 2012.)

I way missed the news window on this one, but I thought it was interesting and a bit underappreciated that the fraction of gold medalists at the 2025 IMO (72/630 = 11.4%) is the highest it’s been since 1981.

Crudely, IMO gold medals are awarded to the highest-scoring 1/12 of contestants.¹ However, because scores are integers up to 42 and there’s no provision for tiebreaking, it’s possible for a lot of contestants to be tied around the threshold. In that case, either all of them get a gold medal or none do, and the fraction of gold medalists might deviate substantially from 1/12. That’s what happened this year: 46 contestants all won a gold medal by scoring exactly 35 points.

Here’s a comparison with the fraction of IMO gold medalists for each year since 2000. (See appendix 1 for a full table and appendix 2 for discussion of the choice of 2000.)

Vim Digraphs: The Unnecessarily Detailed Guide

Sun, 22 Jun 2025 20:17:04 -0700

In Vim, in Insert mode, if you type Ctrl-K followed by two characters, you can insert a special Unicode character corresponding to those two characters. The two-character combo is often easier to remember than other codes. These are called digraphs.

For example, Ctrl-K12 will insert ½.

Everything below this is unnecessary detail.

What are all the digraphs?

I used to think the big table :help digraphs-table at the bottom of Vim’s help page for digraphs was exhaustive. As the page explains, the mnemonics are based on RFC1345, an Internet standard that provides two-character mnemonics for various characters.

Right Back Here

Tue, 31 Dec 2024 14:41:03 -0800

I’m still doing interpretability at Anthropic. This year, among many other research updates, we scaled sparse autoencoders to Claude 3 Sonnet. There’s not a whole lot I have to add. I like to think I improved at various clichéd abstract work skills that I don’t have anything insightful to say about, the most front-of-mind being communication and prioritization. It’s good to, uh, communicate what everybody is prioritizing and communicate all the information everybody needs to prioritize things. Thanks for coming to my TED talk.

In my personal life, I went to more in-person social events than ever before. I took a bunch of improv classes and might actually end up performing soon™. I went to a Jacob Collier concert and a Bear Ghost concert. I scored 141/150 plus two beers on the AMC 12. I attended three separate furry conventions, one of which I believe I have to credit with indirectly motivating me to hit the gym semiregularly for the first time in my life. (Also I went to Tural for summer vacation.) I’m pretty happy with all that, but it also doesn’t really add up to exciting reflections.

How is viridis defined?

Fri, 06 Dec 2024 00:50:25 -0800

If you’ve dabbled in data visualization, there’s a good chance you’ve encountered the colormap viridis, which was created for matplotlib in ~2015.

This particular gradient is brought to you by d3

You may also know about some of the considerations went into the colormap’s design, chiefly perceptual uniformity: equally distant colors on the colormap should “look equally different” to humans.

I won’t discuss color theory much here; the talk introducing viridis (below) is quite good, and there are many other resources online, such as Jamie Wong’s From Hexcodes to Eyeballs or Bartosz Ciechanowski’s Color Spaces.

Instead, I nerd-sniped myself with a different question: How is viridis, specifically, defined?

This seems like it should be easy to answer. Just go into matplotlib and find the source code for viridis, right? Unfortunately, that source code is just a list of 256 RGB triples along which colors are interpolated. This makes sense for efficiency and even portability because (as we’ll see) the formula for producing viridis is incredibly complicated, but it isn’t a very satisfying answer. How did those triples originally come to be?

D3 the Hard FP Way

Sun, 28 Apr 2024 13:15:27 -0700

In theory, the idea here is similar to when I was learning React/Redux and diving into SQL selects. In practice, I think most of D3’s complexity isn’t exactly in a direction that is elucidated by writing down types for everything, so the title is a mere personal snowclone. I’m just writing things out to an arbitrary amount of detail until I understand them and can refer to what I wrote here later.

Background

D3 is “a JavaScript library for visualizing data”. It has a lot of sublibraries that interoperate well but could be used separately — for example, it has utilities for manipulating colors, time, and SVG paths. Of the various concepts, though, I think D3 selections are the most distinctive and fundamental, so they are the focus of this post.

At a high level, D3 selections feel like jQuery. You run some code and it goes into the DOM and adds, deletes, and mutates a bunch of elements. The docs even endorse monkeypatching d3.selection to add custom helpers. However, D3 has data binding and batch operations that make it easy to change the DOM in a way that resembles reconciliation in a framework like React.

Selections

API: Selecting Elements.

A D3 selection holds an array of arrays of nullable¹ DOM elements. The intermediate arrays are called groups. Additionally, each group in a selection is associated with a parent node. During basic D3 usage, you might only ever work with selections with a single group and ignore parent nodes.

When relevant, I will call the index of an element inside its group the “within-group index” and the index of a group among all groups in a selection the “across-group index”.

Despite Everything

Sun, 31 Dec 2023 19:59:03 -0800

…it’s still you. Looking at yourself in the window. The second afternoon after you finally get COVID for the first time.

As previously reported, I left Zoom late last year and spent a bit of time unemployed, traveling for some of it but mostly staying home. In the process, I got COVID, though not with a particularly interesting story. Would not recommend.

Then I started work at Anthropic doing interpretability research — moving way back into my comfort zone in a way by returning to my web dev roots to create many of the visualizations we cared about, and way out of it in another by jumping into the deeply theoretical end of research, in a field where my total experience is one college course and one casual reading group. Still, I figured some things out and we published Towards Monosemanticity in early October.

I don’t have much to add to the research results in the paper, though I can share some trivial, mildly entertaining anecdotes about the process:

Concurrency

Mon, 25 Sep 2023 01:03:41 -0700

I want to add a second word in the title, something like “Koans” or “Vignettes”, but I don’t know a word with the right connotations.

I realized recently that I have been walking around for a long time with some confusion and unknown unknowns about how concurrency works in various settings, and decided to write about it until I stopped being confused. This post doesn’t therefore have much of a “point”.

Concurrency and Parallelism

Wikipedia, as of time of writing:

Concurrency is the ability of different parts or units of a program, algorithm, or problem to be executed out-of-order or in partial order, without affecting the outcome.

There are two broad reasons concurrency is useful. One is for performance: if you want your computer to perform as many floating point operations as possible by lunchtime, you want all CPUs/GPUs/etc. to be performing operations simultaneously. Another is that you’re in a problem domain where you simply can’t predict the order of events: you’re writing a user interface, and the user can click on any of multiple buttons in any order; or you’re writing a web server, and any number of clients can request any pages in any order. These reasons are not mutually exclusive.

Yet Another Diceware-Style Word List

Sun, 23 Jul 2023 00:42:01 -0700

Passwords. It’s 2023 and we still have to deal with them.

Many people know that, per the canonical xkcd, sequences of randomly chosen words such as

soak-science-wander-pew-goldfish-xray-speed-consult
or get the list as .txt or a standalone generator (if my JavaScript were working the above would be a random password and you wouldn’t be seeing this message)

make relatively memorable but hard-to-crack passwords. One popular strategy for randomly choosing words is Arnold Reinhold’s Diceware™, a list of 6⁵ = 7776 “words” that you can randomly sample from by rolling five dice (analog or digital). (I won’t go into topics like how to calculate the entropy of passwords and how long a password you should try to have here, since most Diceware overviews already discuss them at length.)

Somehow this image was already on my blog without being used in any post, but if there’s a post it belongs in, it’s surely this one

A few people have iterated on the concept since then: probably most notably, the Electronic Frontier Foundation published their own word list in 2016, with words chosen to be more well-known and memorable, at the cost of taking longer to type. I’m a fast typer and prefer the EFF’s wordlist over the original, and am very grateful to them for creating it, but after generating quite a few passwords with it over the last few years, I began to feel that it still had a lot of room for improvement.

Designing a Programming Language to Speedrun Advent of Code

Sun, 09 Apr 2023 14:42:52 -0700

“shouldn’t this have been published a few months ago?” yeah, probably. I even considered submitting it to the AoC contest. time is a real beast.

The title is clickbait. I did not design and implement a programming language for the sole or even primary purpose of leaderboarding on Advent of Code. It just turned out that the programming language I was working on fit the task remarkably well.

I can’t name just a single reason I started work on my language, Noulith, back in July 2022, but I think the biggest one was even more absurdly niche: I solve and write a lot of puzzlehunts, and I wanted a better programming language to use to search word lists for words satisfying unusual constraints, such as, “Find all ten-letter words that contain each of the letters A, B, and C exactly once and that have the ninth letter K.”¹ I have a folder of ten-line scripts of this kind, mostly Python, and I thought there was surely a better way to do this. Not necessarily faster — there is obviously no way I could save time on net by optimizing this process. But, for example, I wanted to be able to easily share these programs such that others could run them. I had a positive experience in this with my slightly older golflang Paradoc, which I had compiled into a WASM blob and put online and, just once, experienced the convenience of sharing a short text processing program through a link. (Puzzle: what does this program do?) I also wanted to write and run these programs while booted into a different operating system, using a different computer, or just on my phone.

As I worked on it, I kept accumulating reasons to keep going. There were other contexts where I wanted to quickly code a combinatorial brute force that was annoying to write in other languages; a glib phrasing is that I wanted access to Haskell’s list monad in a sloppier language. I also wanted an excuse to read Crafting Interpreters more thoroughly. But sometimes I think the best characterization for what developing the language “felt like” was that I had been possessed by a supernatural creature — say, the dragon from the Dragon Book. I spent every spare minute thinking about language features and next implementation steps, because I had to.

The first “real program” I wrote in Noulith was to brute force constructions for The Cube, for last year’s Galactic Puzzle Hunt in early August, and it worked unexpectedly well. I wrote a for loop with a 53-clause iteratee and the interpreter executed it smoothly. Eventually I realized that the language could expand into other niches in my life where I wanted a scripting language. For example, I did a few Cryptopals challenges in them. It would take a month or two before it dawned on me that the same compulsion that drove me to create this language would drive me to do Advent of Code in it. That’s just how it has to be.

This post details my thought process behind the design of this language. Some preliminary notes:

2023 MIT Mystery Hunt

Wed, 25 Jan 2023 13:45:37 -0800

My seventh year doing Mystery Hunt with ✈✈✈ Galactic Trendsetters ✈✈✈, and after a hiatus it was in person again! This also makes it my first in-person Mystery Hunt as an alumnus, where I flew in and stayed at a hotel. How time marches on… I appreciated getting to see everybody on Galactic, as well as quite a few internet puzzlers at the location where all the cool people always go, Flour Bakery and Cafe.

Campus hadn’t changed too much. There were more card readers, but also fancy kiosks where ID cards could be printed on demand (via the official 1.2/5★-rated app). I set aside a little time before kickoff to try to locate a working kiosk to print my ID, but the two kiosks I found west of Mass Ave, in W20 and W35, were both out of order; only much later did I print a card in 16. But I am a card-carrying alumnus now. Galactic had two classrooms in 4-2 and lots of masks and tests. One of my teammates brought their dog. It was a fun time.

As typical nowadays, the hunt announcement and kickoff began with a facade theme of a museum. However, the twist was handled a bit differently — kickoff had an additional diegetic level: normally the story is followed by an out-of-character talk about health/safety and policies, but this year that talk, while still in a different universe from the museum, was intertwined with an introduction to MATE, the AI who had ostensibly been writing all the puzzles. Over the course of the hunt, instead of discovering a possibly predictable secret plan or betrayal by MATE, we instead found ourselves on its side because (in the outer fictional diegetic level) teammate had shut off some other “overly creative” AIs and overworked MATE.

One Step Forward to Tomorrow

Sat, 31 Dec 2022 22:19:58 -0800

One day I’m going to run out of the energy to find barely adequate allusions for the titles and thematic music videos for the openings of these end-of-year posts, and they’ll just be called “2095 in Review” or whatever. Or maybe I’ll just stop making them. But not today.

Good song. Good animation. Incredibly out of place on its YouTube channel, in the most inspiring chaotic good way.

I closed out last year by saying that I wanted to accomplish a “big milestone” this year. I actually had a specific milestone in mind that I did not actually achieve and will not reveal, but I made good progress towards it, and a lot of other things happened, enough that I think I’ll count that as achieved.

The big thing is that I left my job at Zoom to have some time for myself and family… though not before helping to give feedback on a draft internet standard, publish a cryptography research paper (on which I’m the “first author”, strictly due to the vagaries of the English alphabet), and launch end-to-end encrypted email. It was a productive year! I feel like I should have more to say about all this, but it’s hard to think of anything that I didn’t already write about last year and also doesn’t require a blockbuster-length list of prerequisites. However, if you ever want to hear about the difficulties of actually getting end-to-end encryption into production in excruciating detail, invite me to a cocktail party with a lot of whiteboards.

Introduction to Code Golf and Golflangs

Thu, 22 Dec 2022 15:46:26 -0800

Code golf is the recreational activity¹ of trying to write programs that are as short as possible.² Golfed programs still have to be correct, but brevity is prioritized above every other concern — e.g., robustness, performance, or legibility — which usually leads to really interesting code.

I think code golf is a lot of fun (although I think a lot of things are fun, so it’s one of those hobbies that I get really into roughly one month every year and then completely forget about for the remaining eleven). I wanted to write an introduction because I don’t know of any good general introductions to code golf, particularly ones that try to be language-agnostic and that cover the fascinating world of programming languages designed specifically for code golf, which I’ll call golflangs for short. But more on that later.

Note: If you are the kind of person who prefers to just dive in and try golfing some code without guidance, you should skip to the code golf sites section.

A simple example

Of course, there’s a reason most code golf tutorials focus on a single language: most code golf techniques are language-specific. The Code Golf & Coding Challenges (CGCC) StackExchange community has a list of some golfing tips that apply to most languages, but there are far more tricks in just about any language-specific list, and most of the intrigue lies in knowing the language you’re golfing well. So to provide a taste of the code golf experience, let’s golf a simple problem, Anarchy Golf’s Factorial, in Python.

In this problem, we have to read a series of positive integers from standard input, one per line, and output the factorial of each, also one per line. Here’s a stab at a simple, direct implementation with no golfing at all:³

def factorial(n):
    if n <= 1: return 1
    return n * factorial(n-1)
try:
    while True:
        print(factorial(int(input())))
except EOFError:
    pass

Flexbox Fun Facts

Fri, 23 Sep 2022 21:33:22 -0700

This post is brought to you by “I am procrastinating other stuff by doing some long overdue maintenance on my blog”. Mainly, I finally replaced the old float-based layout from the random Hugo theme I forked, which I had been keeping just because it wasn’t broken, with flexbox, so that I could more easily tweak some other things. If things look broken, you may need to force-refresh or clear your cache, and on the off chance things look mostly the same but you feel like something about the layout feels subtly different, that’s what’s up.

While making these changes, I ended up digging through the flexbox spec to debug an issue and learned some interesting things. (This and other links in this post are permalinks to the November 2018 spec, which I believe is the most recent official version as of time of writing, but it’s nearly three years and there have been quite a few changes in the “editor’s draft”. Also, this post is not a flexbox tutorial and will not make sense if you are already familiar with flexbox.)

🅿️🅿️🅿️ordle

Mon, 04 Jul 2022 23:54:44 -0700

Don’t you hate it when CTFs happen faster than you can write them up? This is probably the only PlaidCTF challenge I get to, unfortunately.¹

Web is out, retro is in. Play your favorite word game from the comfort of your terminal!

It’s a terminal Wordle client!

I only solved the first half of this challenge. The two halves seem to be unrelated though. (Nobody solved the second half during the CTF.) The challenge was quite big code-wise, with more than a dozen files, so it’s hard to replicate the experience in a post like this, but here’s an attempt.

Mask

Mon, 04 Jul 2022 23:54:33 -0700

Don’t forget to wear your mask…

nc challs.actf.co 31501

If I had a nickel for every CTF challenge I’ve done that involves understanding the internal structure of a QR code, I would have two nickels. Which isn’t a lot, etc etc. That previous challenge probably helped me get first blood on this.

The source code is wonderfully short:

import io, qrcode, string

flag_contents = [REDACTED]
assert all(i in string.ascii_lowercase + '_' for i in flag_contents)

flag = b"actf{" + flag_contents.encode() + b"}"
print("flag is %d characters" % len(flag))

qr = qrcode.QRCode(version=1, error_correction = qrcode.constants.ERROR_CORRECT_L, box_size=1, border=0)
while 1:
    try:
        inp = bytes.fromhex(input("give input (in hex): "))
        assert len(inp) == len(flag)
    except:
        print("bad input, exiting")
        break
    qr.clear()
    qr.add_data(bytes([i^j for i,j in zip(inp, flag)]))
    f = io.StringIO()
    qr.print_ascii(out=f)
    f.seek(0)
    print('\n'.join(i[:11] for i in f))

Kevin Higgs

Mon, 04 Jul 2022 23:54:23 -0700

Now that kmh is gone, clam’s been going through pickle withdrawal. To help him cope, he wrote his own pickle pyjail. It’s nothing like kmh’s, but maybe it’s enough.

Language jails are rapidly becoming one of my CTF areas of expertise. Not sure how I feel about that.

#!/usr/local/bin/python3

import pickle
import io
import sys

module = type(__builtins__)
empty = module("empty")
empty.empty = empty
sys.modules["empty"] = empty


class SafeUnpickler(pickle.Unpickler):
    def find_class(self, module, name):
        if module == "empty" and name.count(".") <= 1:
            return super().find_class(module, name)
        raise pickle.UnpicklingError("e-legal")


lepickle = bytes.fromhex(input("Enter hex-encoded pickle: "))
if len(lepickle) > 400:
    print("your pickle is too large for my taste >:(")
else:
    SafeUnpickler(io.BytesIO(lepickle)).load()

pickle is a Python object serialization format. As the docs page loudly proclaims, it is not secure. Roughly the simplest possible code to pop a shell (adapted from David Hamann, who constructs a more realistic RCE) looks like:

CaaSio PSE

Mon, 04 Jul 2022 23:54:13 -0700

It’s clam’s newest javascript Calculator-as-a-Service: the CaaSio Please Stop Edition! no but actually please stop I hate jsjails js isn’t a good language stop putting one in every ctf I don’t want to look at another jsjail because if I do I might vomit from how much I hate js and js quirks aren’t even cool or funny or quirky they’re just painful because why would you design a language like this ahhhhhhhhhhhhhhhhhhhhh

It’s just a JavaScript eval jail.

#!/usr/local/bin/node

// flag in ./flag.txt

const vm = require("vm");
const readline = require("readline");

const interface = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
});

interface.question(
    "Welcome to CaaSio: Please Stop Edition! Enter your calculation:\n",
    function (input) {
        interface.close();
        if (
            input.length < 215 &&
            /^[\x20-\x7e]+$/.test(input) &&
            !/[.\[\]{}\s;`'"\\_<>?:]/.test(input) &&
            !input.toLowerCase().includes("import")
        ) {
            try {
                const val = vm.runInNewContext(input, {});
                console.log("Result:");
                console.log(val);
                console.log(
                    "See, isn't the calculator so much nicer when you're not trying to hack it?"
                );
            } catch (e) {
                console.log("your tried");
            }
        } else {
            console.log(
                "Third time really is the charm! I've finally created an unhackable system!"
            );
        }
    }
);

Interpreting Some Toy Neural Networks

Thu, 05 May 2022 23:26:13 -0700

I participated in the AGI Safety Fundamentals program recently. The program concludes with a flexible final project, with the default suggestion of “a piece of writing, roughly the length and scope of a typical blog post”, so naturally, I deleted all but the last two words and here we are.

When I previously considered machine learning as a field of study, I came away with an impression that most effort and computation power was going into training bigger, more powerful models; whereas the inner workings of the models themselves, not to mention questions like why certain architectures or design choices work better than others, remained inscrutable and understudied. This impression always bothered me, and it definitely influenced me away from going into AI as a career. Of course, there are important, objective safety concerns around developing and designing models we don’t understand, many of which we discussed in the program; but my discomfort is mostly a completely unrelated nagging feeling I get whenever I’m relying on things I don’t understand.

After the program and all the concurrent developments in AI (including AlphaCode, OpenAI’s math olympiad solver ¹, SayCan, and, of course, DALL-E 2), I still had this impression about the field at a very high level, but I also became more familiar with the subfield of interpretability — designs and tools that allow us to understand and explain decisions by ML systems, rather than treating them as black-boxed mappings from inputs to outputs — and confirmed that enough people study it to make it a thing. One quote from a post on the views of Chris Olah, noted interpretability researcher, captured my feeling particularly eloquently:

interpretability is very aligned with traditional scientific virtues—which can be quite motivating for many people—even if it isn’t very aligned with the present paradigm of machine learning.

I found the whole post insightful, and it happens that the bits before that in the passage were also relevant to me. I don’t have access to lots of compute!

Inspired by that post and by a desire to actually write some code (which I figured might help me understand the inner workings of modern ML systems in a different sense), and after abandoning a few other project ideas that were far too ambitious, I decided to go through some parts of the fast.ai tutorial and riff on it to see how much progress I could make interpreting the models, and to write up the process in a blog post. I tried to capture my experience holistically, bugs and all, to serve as a data point for what it might feel like to start ML engineering (for the rare individuals with a background and inclinations just like mine²), and maybe entertain more experienced practitioners or influence their future tutorial recommendations. A much lower-priority goal was trying to produce “my version of the tutorial”, which would draw more liberally from an undergraduate math education³ and dive more deeply into technical details.

TI-1337 Silver Edition

Mon, 14 Feb 2022 01:32:22 -0800

Last weekend Galhacktic Trendsetters sort of spontaneously decided to do DiceCTF 2022, months or years after most of us had done another CTF. It was a lot of fun and we placed 6th!

Back in the day the silver edition was the top of the line Texas Instruments calculator, but now the security is looking a little obsolete. Can you break it?

It’s yet another Python jail. We input a string and, after it makes it through a gauntlet of checks and processing, it gets exec’d.

#!/usr/bin/env python3
import dis
import sys

banned = ["MAKE_FUNCTION", "CALL_FUNCTION", "CALL_FUNCTION_KW", "CALL_FUNCTION_EX"]

used_gift = False

def gift(target, name, value):
    global used_gift
    if used_gift: sys.exit(1)
    used_gift = True
    setattr(target, name, value)

print("Welcome to the TI-1337 Silver Edition. Enter your calculations below:")

math = input("> ")
if len(math) > 1337:
    print("Nobody needs that much math!")
    sys.exit(1)
code = compile(math, "<math>", "exec")

bytecode = list(code.co_code)
instructions = list(dis.get_instructions(code))
for i, inst in enumerate(instructions):
    if inst.is_jump_target:
        print("Math doesn't need control flow!")
        sys.exit(1)
    nextoffset = instructions[i+1].offset if i+1 < len(instructions) else len(bytecode)
    if inst.opname in banned:
        bytecode[inst.offset:instructions[i+1].offset] = [-1]*(instructions[i+1].offset-inst.offset)

names = list(code.co_names)
for i, name in enumerate(code.co_names):
    if "__" in name: names[i] = "$INVALID$"

code = code.replace(co_code=bytes(b for b in bytecode if b >= 0), co_names=tuple(names), co_stacksize=2**20)
v = {}
exec(code, {"__builtins__": {"gift": gift}}, v)
if v: print("\n".join(f"{name} = {val}" for name, val in v.items()))
else: print("No results stored.")

More precisely, the gauntlet does the following:

blazingfast

Mon, 14 Feb 2022 01:32:15 -0800

Last weekend Galhacktic Trendsetters sort of spontaneously decided to do DiceCTF 2022, months or years after most of us had done another CTF. It was a lot of fun and we placed 6th!

I made a blazing fast MoCkInG CaSe converter!

blazingfast.mc.ax

We’re presented with a website that converts text to AlTeRnAtInG CaSe. The core converter is written in WASM, and also checks that its input doesn’t have any of the characters <>&". The JavaScript wrapper takes an input from the URL, converts it to uppercase, feeds it to the converter, and if the check passes, injects the output into an innerHTML. The goal is to compose a URL that, when visited by an admin bot, leaks the flag from localStorage.

The converter is compiled from this C code:

int length, ptr = 0;
char buf[1000];

void init(int size) {
    length = size;
    ptr = 0;
}

char read() {
    return buf[ptr++];
}

void write(char c) {
    buf[ptr++] = c;
}

int mock() {
    for (int i = 0; i < length; i ++) {
        if (i % 2 == 1 && buf[i] >= 65 && buf[i] <= 90) {
            buf[i] += 32;
        }

        if (buf[i] == '<' || buf[i] == '>' || buf[i] == '&' || buf[i] == '"') {
            return 1;
        }
    }

    ptr = 0;

    return 0;
}

2022 MIT Mystery Hunt

Wed, 19 Jan 2022 19:52:19 -0800

Sixth year hunting with ✈✈✈ Galactic Trendsetters ✈✈✈! As last year’s writing team (previously: 2020, 2019, 2018, 2017, 2016, writing with Random in 2015) we had one final responsibility: running the traditional How to Hunt workshop shortly before this year’s hunt. I didn’t play a huge role in that, but I lurked and reminded myself some things about how new puzzlehunters think about puzzles, and I wrote Yet Another Puzzlehunt Spreadsheet Tutorial after casting around and being not entirely satisfied with the puzzlehunting spreadsheet tutorials I found. I think I actually understand ARRAYFORMULA now.

And then, before we knew it, it was Hunt again.

It’s really nice to get to solve Mystery Hunt again, and especially nice to do so on a team that was fairly actively trying not to win. GT generally tried not to add too many members this year, with some affiliated folks splitting off or hunting with other teams. During the hunt itself, we avoided backsolving puzzles that people were enjoying forward-solving, and encouraged people to be more confident before guessing answers. We ended up with a >50% guess accuracy¹, much higher than some of our past participations, and at least for the puzzles I participated in that took more than a few incorrect answers, I think they were all reasonable guesses or honest mistakes (VALLICELLIANA is difficult to spell) rather than attempts at short-circuiting.

Personally, I did the hunt as part of a roughly 10-person west coast contingent who met up in real life (and who all tested negative for COVID shortly before or after arrival). I think I got roughly three times as much sleep as I did during the 2020 hunt, when we won, and I felt freer to hop onto puzzles that were greatly oversaturated with solvers, such as A Number of Games and How to Install a Handle, or to try less hard looking for extraction steps after doing the fun meat of a puzzle. I think a lot of team members took a similar approach; based on our solve log, we solved no metas between 3am and noon (ET) on either day, and generally had much starker dead zones of activity in the mornings than in past years.

...And They Don't Stop Coming

Fri, 31 Dec 2021 23:59:00 -0800

It’s another year, huh.

2021 is the first year during which I held a full-time job continuously. My disposable income and discretionary spending have both increased the most sharply since, well, ever. It’s weird.

We are still in a pandemic. Greek letters continue to be associated with uncool things. I got vaccinated and started taking measured (but still small) risks. Funny story: my first vaccination was a complete surprise, as my roommate knocked on my door mid-day to inform me that somebody he knew had extra vaccines to give out — except that the night before I had a dream about being vaccinated, which was weird enough that I wrote that dream down, something I do only once every few months. I also got boosted just a few days ago.

What else happened to me in 2021?

Just Enough Elliptic Curves to Be Dangerous

Sun, 28 Nov 2021 18:24:18 -0800

A famous Trail of Bits post says to stop using RSA: it’s simple enough to make people think they can implement it correctly, but full of invisible traps. In contrast, although elliptic curve cryptography (ECC) implementations could also fall into subtle traps, they usually don’t. The post conjectures that this is because ECC intimidates people into using cryptographically sound libraries instead of implementing their own.

If you do want to understand ECC just enough to produce your own trap-ridden implementation, though, this post aims to get you there. (Assuming some mathematical background chosen in a not particularly principled way, approximately what I had before writing this post.) Hence the title. Because I have a cryptographic conscience, I will still point out the traps I know of; but there are probably traps I don’t know about.

This post contains a lot of handwaving and straight-up giving up on proofs. You don’t need to know the proofs to be dangerous. The ethos is sort of like Napkin, but way shoddier and with zero pretense of pedagogical soundness. Still, here are some concrete questions that I learned the answer to while writing this post:

Why does the group law hold, sort of intuitively?
Why do people have to modify Curve25519 before using it to compute digital signatures?
What is a “quadratic twist” and why should I care about it to pick a secure elliptic curve?
How is it possible that an isogeny can be described as surjective but not injective while mapping a finite elliptic curve to another elliptic curve of the same cardinality?
How many claws does an alligator have?

Elliptic curves have a lot of complicated algebra. If you ever studied algebra in high school and did exercises where you had to simplify or factor or graph some really complicated algebraic expression, and you learned that algebra is also the name of a field in higher mathematics, you might have assumed that working algebraists just dealt with even more complicated expressions. If you then studied algebra in college, you’d probably have realized that that’s not really what algebra is about at all; the difficulty comes from new abstractions, like a bunch of the terms above.

Well… the study of elliptic curves involves a bunch of complicated expressions like what your high school self might have imagined. Sometimes, notes will just explode into a trainwreck of terms like

\[\begin{align*}\psi_1 &= 1 \\ \psi_2 &= 2y \\ \psi_3 &= 3x^4 + 6Ax^2 + 12Bx - A^2 \\ \psi_4 &= 4y(x^6 + 5Ax^4 + 20Bx^3 - 5A^2x^2 - 4ABx - A^3 - 8B^2).\end{align*}\]

“This is REAL Math, done by REAL Mathematicians,” one is tempted to quip. The Explicit-Formulas Database is a fun place to take a gander through. I will copy formulas into this post from time to time when there’s something about them I want to call attention to, but in general we won’t do any complicated algebraic manipulations in this post. Just be prepared.

Because I’m focusing on conceptual understanding (and am lazy), this post contains almost no code, and definitely no code that’s runnable in any real programming language.

One Weird Anki Trick

Mon, 16 Aug 2021 01:35:57 -0700

Imagine you had a button you could press whenever you saw or heard something you wanted to remember. By holding that button down for about a minute, you’ll be able to remember that thing forever. There are no undesirable side effects. Sounds like a pretty good deal, right?

There’s only one catch: you have to regularly find new things to press the button on. If you stop for more than a few days, the effects wear off. If you ask me, it still seems almost too good to be true! But it’s not. It’s the magic of spaced repetition.¹

I had known about this magic for a long time and read blog posts from all directions telling me to use it, typically but not necessarily through Anki. Examples include Nicky Case’s interactive guide and Alexey Guzey’s guide; and because this has been so well-covered, I won’t go into how or why spaced repetition works or how one would use Anki in this post. Still, for a long time, I found the one “catch” to be of the -22 variety: I didn’t use Anki regularly because I didn’t have any flash cards of things I wanted to remember; but I didn’t make any flash cards of things I wanted to remember because, given that I didn’t use Anki regularly, making those flash cards wouldn’t actually help me remember those things.

Here is the One Weird Anki Trick that got me to finally turn spaced repetition into a habit: I created an Anki deck with a bunch of amusing but utterly useless cards,² in order to make studying the Anki deck an entertaining activity I actually wanted to do. (Getting the mobile app and syncing my deck online also helped a lot.) Only after I started to habitually check my Anki deck did I start adding cards for the things I actually wanted to learn. I keep everything in one deck,³ so that my fun cards are spread out among my “work” cards, and when I find myself losing motivation, I add more useless entertainment cards.

That’s it. That’s the whole post.

What Color Should My Discord Roles/Reactions Be?

Mon, 28 Jun 2021 20:17:51 -0700

I subscribed to Discord Nitro a month ago, but only recently did I start thinking about the full range of powers the subscription granted me. I could create my own reactions, dump them in my personal server, and use them to react anywhere.

However, when I finally started trying to create some reactions, I hit an interesting snag: Discord can be used in dark and light mode,¹ and a reaction will have the same color on both modes. If I wanted my reaction to be as clearly readable in both modes as possible, what color should I make it?

(I could, of course, just outline my reaction with a contrasting color, but let’s say that’s cheating. With the limited space in a reaction, outlining isn’t that great of a solution anyway.)

Now, one can’t really just compute the “contrast of two colors” given only their RGB components; there’s no universally agreed-on definition of contrast in vision, and even if there were one, the contrast of two given colors would depend on the color space and possibly the viewer’s biology. But, to get a concrete answer to this question, we can use the standard sRGB model and the W3C’s definitions of contrast ratio and relative luminance.² As of time of writing on my computer,³ Discord reactions have background #2f3136 on dark mode and #f2f3f5 on light mode. Reactions you’ve reacted with have background #3b405a on dark mode and #e7e9fd on light mode. Because the dark mode background gets lighter and the light mode background gets darker, we’ll use the latter colors so we’re optimizing the worst-case contrast.

There are smarter approaches, but the 256³ = 16,777,216 possible 8-bit colors are perfectly feasible to brute force, so I wrote a short Python script to check all of them, which is at the bottom of this post. Under the parameters I’ve outlined, the optimal color for a Discord reaction is rgb(255, 65, 3) or #ff4103. A demo:

#ff4103 #ff4103 ●
CR: 2.90738237

#ff4103 #ff4103 ●
CR: 2.90738217

That was simple enough, but this color’s worst-case contrast ratio is less than 0.0000002 better than the runner-up. Surely even very mild aesthetic considerations will outweigh that. (It’s highly doubtful that the formulae I used were intended to have this degree of precision in the first place.)

After playing with a few ways to get a spread of options, I settled on categorizing colors into six buckets of saturation and twelve buckets of hue in the simple HSV model, and then finding the optimal color within each bucket. Here is a table of my results:

SQL Selects the Hard FP Way

Fri, 16 Apr 2021 19:41:49 -0700

This post is motivated by reasons very similar to the ones that motivated my React and Redux “tutorial”. Again, it should be more accurately but less informatively titled “How I wish SQL SELECTs were explained to me”. Again, it does not imply that this method of explanation is suitable for anybody else. One difference is that this time, I mostly only wanted to learn about SQL SELECTs to the extent it would help me perform and optimize queries in Django’s ORM, but to prevent this post from languishing forever in my drafts folder, that material has been sectioned off into a possible future post, because I figured out what I wanted, ran out of steam, and am now trying to learn TLA⁺. Just me things.

Background

The SQL standard is confusing and almost never completely implemented; there are huge inconsistencies between SQL implementations. I will focus on SQLite because it’s popular and easy to play with, but generally try to stay away from unpopular or nonstandard features. SQLite’s SELECT documentation is good reading for one particular SQL implementation.

A SQL database is a place where you store and query a bunch of data that’s organized into tables. A table is a homogeneous list of rows. A row is a heterogeneous tuple of values of various simple data types. The data types supported depend on the SQL implementation; typical examples are integers and strings of various sizes, floating point numbers, and dates/datetimes. All of these types can be nullable; NULL is a SQL value that can appear just about anywhere. (Like many of the other SQL features, NULL is handled somewhat inconsistently across SQL implementations, but as a first-order approximation it’s closer to a floating-point NaN than, say, Java’s “null”. We’ll talk more about it later.) However, note that you can’t have a variable-size list of other things in a row. And just to make sure it’s clear, all the rows in a given table must have the same data types in the same order.

A “column” is just what you’d intuitively expect it to be: it’s the homogeneous list of all values in a particular position in each row of a table, which all have the same data type. One thing I haven’t mentioned yet is that table columns all have names. This is true both for tables stored in the database and for the ephemeral tables that are the output of queries.

Since I’ll also be referring to more complex types like lists and tuples often seen in conventional programming languages, I’ll call these simple data types “scalar types” and values of those types “scalars”. This is not SQL terminology; documentation usually just calls these “data types”. Here’s SQLite’s page on data types.

To play along, install SQLite and run it. You should get dropped into a connection to an ephemeral in-memory database, which is plenty enough for our purposes. Make a table and mutter some magic incantations to make the output a little prettier for us:

CREATE TABLE a (id int);
INSERT INTO a VALUES (1), (2), (3), (4);
.headers on
.mode column

Blogging Advice For People Exactly Like Me

Sun, 14 Mar 2021 00:24:46 -0800

Did you know that it’s harder to become an MIT admissions blogger as an MIT student than it is to get into MIT as an applicant? It was true my year, in which 18,306 students applied and 1,467 were admitted (8.0%),¹ whereas 69 students applied for 5 blogging spots (7.2%).² Anecdotally it might also be true for future years.

I was among the 92.8% who got rejected in the latter process. Although I obviously would have preferred things go the other way, I can’t say I was surprised, firstly because, objectively, the odds were against me (as they were for every other individual applicant); secondly because, to the extent I can make educated guesses about the criteria the folks at MIT Admissions would have chosen bloggers by, I would have been close to the worst possible candidate;³ thirdly because my application probably wasn’t very good.⁴

I didn’t dwell on it; I just thought to myself some vague consoling thoughts and moved on. No matter what I missed out on, at least I retained complete freedom: to choose what to write about, when to post it, and how to format and typeset it, down to the very last box-shadow. Right? But, although I mostly successfully avoided thinking about it, there really was a lot to like about being an admissions blogger! I liked writing — or perhaps, I liked being a person who has written a lot more, and having a commitment to blog regularly would be a way to force myself to become that person. I liked the idea of getting to share things with thousands of readers, or less euphemistically I liked the thought of being, if ever so slightly, famous.⁵ I liked the idea of having a sketched portrait and being part of official events with “Blogger” in the title and all that jazz. Collectively these things just felt cool.

The thing is, though, that there were things I could do to try to get those things for myself, and I didn’t do them. I know how to force myself to blog regularly, which is just by announcing publicly to nobody in particular that I’ll blog regularly (it’s worked effectively at least twice). I know many places I could promote my blog and try to get more readers. I can buy a sketched portrait.⁶ It’s not that hard.

2021 MIT Mystery Hunt

Sat, 13 Feb 2021 16:07:56 -0800

Note: if you are viewing this shortly after it’s published and somehow don’t want to be spoiled on Mystery Hunt, make sure this spoiler formatting shows up: this text should be spoilered; if it doesn’t, try shift-refreshing. (There are Correct Ways to fix this, but I’m too lazy to do them. Sorry.)

Well, we did it.

✈✈✈ Galactic Trendsetters ✈✈✈ ran an MIT Mystery Hunt.

Somehow, it slipped my mind until trying to write the 2020 year-end post that I’d probably want to write a post on all this. In fact, there was one major project that I started in 2019, but that I didn’t think of mentioning in my 2019 year-end post because it wasn’t ready to be announced at that time, and that I almost forgot that I had never mentioned. But this post is a pretty good place to announce it.

Planning Mystery Hunt is a massive year-long endeavor. I didn’t have any leadership or otherwise high-responsibility roles, which made sense because I was busy writing a masters thesis for the first four months of Mystery Hunt planning. Because of that, and because I know many many other people on our team have written and will be writing blog posts (Rahul’s post, Nathan’s post, CJ’s post, maybe more to come?) I will focus on the things I did specifically. (So there is minimal discussion of the theme, overall organization, or big decisions like our COVID-19 response; I think the linked posts cover these well already.)

Puzzle-Writing Software

One part I did largely have “ownership” of, and that I sank a lot of time into, was maintaining our software for writing puzzles — the website where authors submitted puzzle ideas and drafts, testsolvers tested puzzles, and editors tracked and discussed the statuses of all the puzzles. This role was largely a continuation of me owning the same component for Galactic Puzzle Hunt since 2018, which itself grew out of the comparative advantage of having worked on it a little when writing with Random Fish for the 2015 MIT Mystery Hunt. There is some life lesson about specialization or pigeonholing to be learned here. But, to start at the beginning:

Puzzletron is a piece of PHP software used for organizing puzzle writing for puzzlehunts. The first commit on GitHub says it was imported from Metaphysical Plant in 2011; it’s likely older. There are active commits each year until January 2018, and AMA responses from Setec (2019) and Left Out (2020) mentioning it, so I believe most if not all Mystery Hunt writing teams used and improved Puzzletron and passed it down over those years.

…And I Feel Fine

Thu, 31 Dec 2020 23:59:00 -0800

It’s a strange and darkly funny story — Tim Minchin wrote the album this is from, Apart Together, well before the pandemic hit and social distancing became the norm, and I assume I am not alone in finding that the song resonates unusually strongly as a result.¹ By Jove, it resonates.

Nobody needs me to say that it’s been a rough year. People have been complaining that each of the last few years were terrible, and looking forward to the next one, and being disappointed — as if years were coherent bundles of quality, and there was any reason to expect discontinuities in how things are going to occur around January 1st — and as if there were additionally any reason to expect such discontinuities, if they did exist, to be positive ones.

Seriously, do you remember when we thought 2015–2018 were bad?

And yet… I feel like overall, 2020 went quite a bit better than expectations for me. Which maybe means it’s astronomically better than the average person’s 2020. I had a long draft for this post that slowly accumulated words over the year as usual, but a lot of the ramblings I’d usually include now seem unusually vapid, and a lot of the deeper trends and experiences I might normally reflect on are things I don’t think I’ve really gone through or thought about for long enough to achieve closure on. This is partly due to the pandemic scrambling a lot of plans and partly because last January, nearly a full year ago, ✈✈✈ Galactic Trendsetters ✈✈✈ won Mystery Hunt and so we’re writing the 2021 hunt. The ramifications are still being felt and will accelerate until it actually happens two weeks from now, and that’s all I’ll say about it here.

Advent of Code: How to Leaderboard

Tue, 24 Nov 2020 19:13:19 -0800

Advent of Code (briefly, “AoC”) is a series of 25 festive programming puzzles¹ released daily December 1–25. Each puzzle has two parts, which use the same text input and are related; to solve a part, you submit the right output corresponding to the input on the website.

If you’re reading this, I suspect there’s a good chance you knew that already, but in case you’re new to Advent of Code, let me try to briefly explain why I like Advent of Code, from the perspective of somebody who’s spent a lot of their life so far doing programming competitions.²

The event has a fantastic community surrounding it. I’m the most familiar with the subreddit, which is full of helpful people, interesting discussions, non-programming community games, and the occasional wonderfully, spectacularly overengineered solution to a puzzle; but I know there are also many smaller chatrooms and subcommunities focused on, say, specific timezones or programming languages.
Another aspect is the unique two-part format of each puzzle. Even though they use the same input, you don’t get to see the second part until after you’ve solved the first one, a feature that Eric Wastl (AoC’s creator) has taken full advantage of in designing puzzles. The second part is often a surprising twist on the first part, which keeps you on your toes and challenges you to keep your code moderately general or refactorable in a way that I think almost no other programming challenges do. This sometimes even happens between days in a calendar, when a puzzle turns out to be about some model of computation you implemented two or five or ten days ago — hope you kept your code and remember how it works!
Finally, AoC also has some non-rigorous puzzles that force you to use your intuition and “human intelligence”, either by interpreting the problem statement heuristically or writing code to let you explore the input. There are quite a few puzzles where it’s infeasible to write code that handles every step of obtaining the output from the input. The result is that Advent of Code can feature quite a few challenges that I’ve found particularly compelling because I think they simply could not be posed on any other contest platform.³

These are the things that make AoC stand out to me, but it also does a lot of other things well — the challenges are fun, approachable, and varied even aside from their interrelations; there is a long, dramatic story tying everything together (although it’s an Excuse Plot if there ever was such a thing); and, although this is obviously subjective, I find the website’s minimalist-adjacent, terminal-esque aesthetic really charming (there is a lot of detail in 2019’s calendar… after you solve everything). I’ve only done the last two years of Advent of Code, but it really seems like a one-of-a-kind event to me.

Anyway, one particular feature Advent of Code has is a leaderboard, which you can get on by being one of the first 100 people worldwide to solve each puzzle. The competition is fierce — every year, thousands of people compete to get on the leaderboard. Near the start of AoC 2019, mcpower (reddit discussion) and Kevin Yap (reddit discussion) wrote some articles about how to do this, both of which are worth reading. I also thought about writing such an article and started a draft, but I didn’t get it anywhere close to publishable before AoC had concluded, at which point I assumed few people would be interested. But here it is now.

C++ Rvalue References: The Unnecessarily Detailed Guide

Mon, 16 Nov 2020 00:25:50 -0800

By a strange quirk of fate, I have started writing C++ for a living.

Learning C++ was about as complicated as I think I expected it to be. By line count, I’ve written a lot of C++ for programming competitions, but I knew that I had only ever used a small cross-section of the language: basic control flow and variables, STL containers and algorithms, structs on which you mechanically define bool operator<(const T& other) const so STL algorithms can order them, and the very occasional macro or templated helper function. There were many features I wasn’t even aware existed.

In the process of learning C++ professionally, one rabbit hole I fell into quickly was C++11’s defining feature, the rvalue reference, and how it can be used to implement move semantics and perfect forwarding. By poring over a copy of the widely recommended book Effective Modern C++, by Scott Meyers, and a few dozen StackOverflow answers and blog posts, I roughly understood it after a few days, but still had a sort of blind-men-feeling-the-elephant feeling. I was confused about what lay under some of the abstractions I had been using, unsure of the full shape of the pitfalls that some of the guides had pointed out to me, and generally uncomfortable that there were still many small variations of the code I had seen that I couldn’t predict the behavior of. It took many more days to work myself out of there, and I wished I had had a guide that explained rvalue references and their applications to a bit more depth than what might be necessary for day-to-day use. So here’s my attempt to explain rvalue references in my own fundamental I-want-to-know-how-things-work-no-really style.

(If this vision doesn’t resonate with you, there are many other posts explaining rvalue references out there that you might prefer. Feel free to just skim the executive summary and/or check out some of the linked articles in the Background section.)

Executive Summary

I got… pretty carried away when writing this post, and a lot of it is just for my own understanding, which may or may not be useful to readers. Here’s a much more concise rundown (assuming you know basic C++ already):

45/101

Tue, 12 May 2020 23:06:51 -0400

Not a very completionist run. I graded myself pretty strictly though — both sides of every “and” need to count; “all” means literally all; fuzzy actions and phrases require full psychological commitment to qualify.

Signed Modulo

Tue, 04 Feb 2020 18:00:58 -0500

One thing many mathematically-inclined programmers run into when implementing mathematical algorithms, particularly number-theoretic ones, is that the modulo operation doesn’t behave how they expect or prefer.

In many languages, this operator is denoted %. Concretely, one might prefer that, if the second argument is positive, then the modulo operation would always give a nonnegative result. Under this behavior, the expression (-5) % 3 would evaluate to 1 rather than -2. This is a lot more useful for number theory because then for positive integers n, the % n operation actually maps integers to exactly the n canonical representatives for the residue classes. As a result, $a \equiv b \mod n$ if and only if a % n == b % n. You can also do things like index into a length-n array with a % n and know that the index will be in-bounds. Finally, there are also optimization opportunities: modding by a power of 2 becomes equivalent to a simple bitwise AND, which is really fast on modern computers.

A few programming languages, notably Python, do implement % this way. However, the majority of languages today, including pretty much everything remotely descended from C, do not; instead, (-5) % 3 is -2. This post attempts to track down why.

The first thing to note is that there is a more important number-theoretic identity we’d like to have:

\[\texttt{a} = (\texttt{a / b}) \cdot \texttt{b} + (\texttt{a \% b}). \tag{1}\]

In words, the integer division and modulo operators should give a breakdown of a into a sum of some copies of b plus a remainder. Note that this equation also implies that specifying the rounding behavior of division is equivalent to specifying the sign behavior of the modulo operation, which will come up repeatedly later.

It’s also very uncontroversial that that remainder should have no copies of b, positive or negative, left over, which gives the constraint:

\[|\texttt{a \% b}| < |\texttt{b}|. \tag{2}\]

Every programming language I can think of satisfies these two constraints.¹ So far so good. However, these two constraints don’t uniquely determine the values of a % b when a isn’t divisible by b; there are two possible values for a % b, one positive and one negative. Concretely, we could express $-5$ as either $(-1) \cdot 3 + (-2)$ or $(-2) \cdot 3 + 1$, so (-5) % 3 could be -2 or 1.

It’s still mostly uncontroversial that, if a and b are both positive, then a % b should be nonnegative as well; we could call this constraint (3).² However, if a is negative and b is positive, programming languages start to diverge in their behavior. Why?

2020 MIT Mystery Hunt

Mon, 03 Feb 2020 23:24:47 -0500

Fifth year with ✈✈✈ Galactic Trendsetters ✈✈✈ (previously: 2019, 2018, 2017, 2016; writing with Random in 2015).

We won!

But apparently I’m still really busy, so I’ll probably just focus on a few highlights of things I personally experienced and get this post out the door.

The theme in a few sentences: As suggested by the invitation sent out to teams, there was a wedding. It turned out to actually be a real wedding between two prolific puzzle writers on Left Out, the organizing team. To the surprise of everybody who expected either one, three, or maybe five subversions of this announcement, the wedding actually succeeded (a COIN that would prevent all love in the universe was briefly reported missing, but then immediately found by the bride). Instead, we joined the newlyweds on a trip to an amusement park called Penny Park, which we learned was struggling and closing this weekend. It was up to help its regain its popularity and stay open by solving puzzles. The Mystery Hunt subreddit has lots of other cool links and discussions, including this animated bar chart, so I won’t spend more time here.

I’m pretty sure the best story I personally experienced was how we solved the metameta, the biggest puzzle that stood between us and winning hunt, and the moment at which we went, holy smokes we might have won Mystery Hunt! We got all the pennies required for the final metameta at Sunday 5:48:09am, and it took us until 12:47:30pm, just under seven hours later, to solve it…

Startup Lag

Tue, 31 Dec 2019 16:24:31 +0800

This is a weird song choice — I have not even watched the movie. But there is a story, and there is a thematic correspondence.

The story is that I was interning remotely at a coworking space over the summer. One night, I attended a karaoke event hosted there, the kind where adult human beings socialize and where I didn’t know anybody else, and I sang this song. Afterwards, another attendee told me that her kid (yeah, you know, people in my reference class have children) loved Moana and was really excited about my performance.

The thematic correspondence is less obvious and harder for me to describe. I’m going much less further this year than I could be, and am less sure about next year than I expected to be at this point for reasons I’m not ready to share yet (this seems to be happening more and more on this blog, but there’s not much I can do about it — so it goes). But it really is the case that there are some things I can’t deny about myself, some attractor states that my values and way of thinking keep dragging me towards.

Frivolous examples: I went through another online Dominion phase and at least two Protobowl phases, the highlight of which is learning a good deal about Émile Durkheim and then buzzing on him the next day. I did Advent of Code again, with the same golfing setup as last year, a foray into making an auxiliary over-the-top leaderboard in Svelte, and (surprisingly to myself) getting first. I have a shiny Charizard with Blast Burn now.

Rocket Equation

Sun, 01 Dec 2019 13:38:14 -0500

It’s December, so it’s time for a lot of things, including Advent of Code. I will not be able to be as competitive as I was last year, and already lost a lot of points to a really silly mistake on day 1, but I’ll be playing when I can and golfing the problems when I have time (so far: 7 + 14 bytes).

As one might expect, Day 1 is not too complex, but the second part can be analyzed to some mathematical depth and was discussed a bit on Reddit; plus, it occurred to me recently that I set up KaTeX on my blog but never used it, so I was looking for an excuse to write some equations anyway.

The problem statement for part 2, in brief: We are tasked with calculating the total mass of fuel required to launch a rocket module of a given mass. For something of mass $m$, one can compute the directly required mass of fuel by dividing $m$ by 3, rounding down, and subtracting 2; if the result is negative, it is taken to be 0 instead. However, the directly required fuel also requires fuel itself, calculated from its own mass by the same procedure, and that required fuel requires fuel based on its own mass, and so on until you reach fuel with 0 requirement.

callsite

Mon, 16 Sep 2019 01:18:58 -0400

Call me maybe? nc rev.chal.csaw.io 1001

A rev with a nasty binary. There are so many functions. I do not like this binary.

Static Analysis

After staring at the sea of functions in IDA for a little bit, I gave up and tried dumb things instead.

unagi

Sun, 15 Sep 2019 23:43:10 -0400

come get me

http://web.chal.csaw.io:1003

This was a web challenge with a few pages. The “User” page displayed some user information:

Name: Alice
Email: alice@fakesite.com
Group: CSAW2019
Intro: Alice is cool

Name: Bob
Email: bob@fakesite.com
Group: CSAW2019
Intro: Bob is cool too

The “About” page simply told us, “Flag is located at /flag.txt, come get it”. The most interesting page was “Upload”, where we could view an example users XML file:

baby_boi (A Textbook CTF ROP Tutorial)

Sun, 15 Sep 2019 22:12:04 -0400

Welcome to pwn.

nc pwn.chal.csaw.io 1005

Ahhh, CSAW CTF. Amidst all the other CTFs where we’re competing with security professionals who probably have decades of experience and who follow security developments for a living or whatever, there remains a competition where scrubs like me can apply our extremely basic CTF skills and still feel kinda smart by earning points. Now that I’ve graduated and am no longer eligible, our team was pretty small and I didn’t dedicate the full weekend to the CTF, but it means I got to do the really easy challenges in the categories that I was the worst at, by which I mean pwn.

baby_boi is pretty much the simplest possible modern ROP (the modern security protections NX and ASLR are not artificially disabled, but you get everything you need to work around them). We even get source code.

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv[]) {
  char buf[32];
  printf("Hello!\n");
  printf("Here I am: %p\n", printf);
  gets(buf);
}

So there’s nothing novel here for experienced pwners, but I feel like there is a shortage of tutorials that walk you through how to solve a textbook ROP the way you’d want to solve it in a CTF, so here is a writeup.

Introduction to Puzzlehunts

Mon, 02 Sep 2019 10:34:38 -0400

not part of the ongoing series, but you can almost pretend it is. This sentence and the one before it are not a puzzle.

Imagine a word search.

Now imagine you aren’t told what words to look for.

Now imagine you aren’t told it’s a word search.

Now imagine it isn’t a word search.

— Mike Develin, via Thomas Snyder (aka Dr. Sudoku)

This post aims to be a fairly comprehensive introduction to puzzlehunts and their puzzles, a single post where I can just point people. I erred towards comprehensiveness in this post because I am not aware of any similar resources, especially for puzzlers interested in trying harder puzzlehunts who might not know any more experienced puzzlers to solve with. It’s possible to start solving some puzzles after reading much shorter guides, e.g. Puzzled Pint’s “Puzzling Basics” (PDF), so feel free to skip around, stop reading midway through, or bookmark this to read only after you’ve spent more time solving.

What is a Puzzlehunt?

A puzzlehunt¹ is an event where people, usually in teams, solve a series of puzzles.

This is not a very useful definition. The more interesting question is, what is the kind of “puzzle”² that appears in a puzzlehunt? The concept of a puzzlehunt puzzle is fuzzy and difficult to define precisely. Just about any hard rule one might try to state will be broken by some puzzle, sometimes deliberately. Still, here are some common features of puzzlehunt puzzles:

Cook Like You're Not on MasterChef

Fri, 23 Aug 2019 00:37:43 -0400

part of the “what I learned after four years at MIT” series, I guess?

When I was very young, I thought cooking was easy. I sliced plastic vegetables with a toy knife and then Velcroed them back together, ad infinitum. For at least some time, I wanted to be a chef when I grew up.

When I was slightly less young, I thought cooking was hard. My reference points were mostly (1) my parents, who seemed to know how to make a million different dishes in inscrutable ways without thinking, and (2) MasterChef contestants (who I assume were better at cooking than my parents because they were, well, on MasterChef) messing things up and getting kicked off the show.

Now, I think I probably elided some meaningful distinctions there in my youthful naïveté. Cooking food that will keep you from getting kicked off MasterChef is hard. Cooking edible food is easy.¹ Cooking storebought dumplings in particular is so stupidly easy it’s unfair. More generally, though, most recipes tolerate a lot of substitutions,² number fudging,³ and even straight-up skipping pesky instructions, like the ones in baking recipes where you mix two sets of ingredients separately in specific orders. There are reasons for those steps, but ignoring them and dumping everything into the same mixing bowl usually won’t make your results inedible. You can also just decide to omit ingredients you don’t like. Probably the least tolerant ingredient measurements in recipes are the measurements of baking soda or baking powder, which by the way are different things, in baking recipes. But otherwise you’d really be surprised how many corners you can get away with cutting — I’ve even completely winged one baking soda/powder measurement with decent results. I think this is especially important to know for people from technical backgrounds like me, who have an instinct to treat the numbers in recipes as precisely measured, painstakingly optimized choices to produce the best dish. They usually aren’t, and even if they are optimized for the recipe author’s palate, they probably won’t be optimized for yours.⁴ And they certainly aren’t optimized for any tradeoffs you might want to make between food quality versus the time and effort you’re putting into cooking. Make the tradeoffs you want. You’re not on MasterChef.

Money Matters

Wed, 21 Aug 2019 23:34:04 -0400

part of the “what I learned after four years at MIT” series, I guess?

There’s some oft-cited psychology studies that suggest that once your salary goes above $75,000, additional money doesn’t make you happier. This sounds like a sage bit of life advice if it were true, the ultimate rebuff against excessive greed and materialism and sacrificing other things for a six-digit salary, but it overstates the case a bit. 80,000 Hours’ analysis of money and happiness is probably the analysis I’d trust the most here; I think it would be more accurate just to say that you get diminishing returns of happiness from salaries above $70,000.¹ Still, that was enough for me to decide fairly early on that I wasn’t interested in trying to get a high-paying job for its own sake, or in spending too much effort trying to invest my way to a fortune.² I wanted my job to be personally satisfying and good for the world, while paying enough for me and my family (current and future) to get by, but I planned to treat any additional money after that as little more than a bonus used for breaking ties.

I still mostly stand by that decision today, but over the intervening years I realized there were a whole host of reasons to want money that weren’t that selfish at all.

Go to Class (Most of the Time)

Mon, 19 Aug 2019 09:10:43 -0400

part of the “what I learned after four years at MIT” series, I guess? A short post this time.

I can’t begin to count the number of times we were exhorted in high school to go to class. College is different, they said. Nobody is going to force you to go to class any more. This is what you came to college to do, what you paid so much time and money for. It’s on you to make sure you’re learning.

By and large I followed this advice, until I considered that I might have overcorrected given the exhortations. There are a lot of definitely bad reasons to skip class, chief among them being too lazy to get out of bed. There are also some non-obvious reasons to go to class, such as getting the professors to recognize you — this is a reason to go to office hours even if you’re not particularly struggling with the class, or if you know people who might be able to help you that you could ask more comfortably or more conveniently; professors who know you may eventually be able to give you career advice, research opportunities, or letters of recommendation. (Of course, you shouldn’t try to befriend professors purely for these selfish motives; they’re also good to know just as fellow humans.)

But there are also plenty of legitimate reasons to skip class. (It’s really unclear how many people out there need to hear this, but my past self did, and I want this draft out of the way-too-long queue of posts.) Here are some.

Multiplication by Juxtaposition

Sun, 04 Aug 2019 09:49:20 -0400

We interrupt the irregularly scheduled philosophical posts for some programming memes:

Over the last few days, the Internet has divided itself over what the value of the expression 8÷2(2+2) should be. Some say it should be evaluated as (8÷2)×(2+2) = 16. Some say it should be evaluated as 8÷(2×(2+2)) = 1.

At the risk of belaboring the obvious, the core dispute here is not really mathematical. There is not some sequence of mathematical operations that produces some number, where mathematicians disagree about what number it produces. Instead, this is a dispute about mathematical notation: what sequence of mathematical operations the expression corresponds to the way it’s written. Specifically, it is a dispute about whether multiplication written as juxtaposition (how “2” is written right next to “(2+2)”) has strictly higher precedence than division. It is closer to a linguistic or typographical dispute than a purely mathematical one, and the correct answer to the dispute is that whoever wrote the expression that way should learn to write math better.

This debate is not even new. The internet had fun arguing over 48÷2(9+3) and 6÷2(1+2), which are functionally identical ambiguous expressions, eight years ago. I don’t know why the debate is resurging now and why we still haven’t gotten tired of it.

But life is short, so since we’re here anyway, let’s make some additional memes.

Asking the computer

Some of my coworkers had the idea to ask some programming languages what the answer was. The results were underwhelming.

$ python3
Python 3.6.7 (default, Oct 22 2018, 11:32:17)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 8/2(2+2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not callable

Writing for the Mundane

Thu, 01 Aug 2019 21:23:15 -0400

part of the “what I learned after four years at MIT” series, I guess?

I hated timed essays in high school. It’s pretty clear if you skim that part of the blog archives:

My [SAT] essay got a 10 out of 12. It’s an essay I’d be ashamed of posting anywhere else; it’s disgustingly traditional and formulaic. […] This was simply because I knew that using my normal essay-writing mindset, I’d get maybe a 3, because I’d spend the first twenty minutes debating myself over which side I was on and rewrite the introduction ten times. Too bad. I wasn’t there to write a good essay; I was there to get a good score on the SAT.

The worst issue is that students do not need to give in-depth explanation of anything they learned. Due to its stringent time limit, the essay portion rewards quick reckless writing much more than deep thought. […] encouraging students to practice writing 25-minute essays in order to improve their college-bound skills is like encouraging people to play Grand Theft Auto in order to improve their driving skills.

I took the Grand Theft Auto analogy pretty far. I’m not proud enough of these posts to link them, but you can find them if you try. In short, past me thought timed essays rewarded writing too quickly, with a disregard not only for facts but for the opportunity to lay out your opinions and thoughts so you could clarify and revise them, which was actually the most valuable part of writing.¹ I conceded that the time limits made sense as a practical concession to allow you to test students’ writing skills fairly,² but I felt like there was still way too much emphasis on the raw speed.

Things

Sun, 23 Jun 2019 16:40:07 -0400

Part of a series of posts about what I learned after four years at MIT. We’re ramping up to deeper topics eventually, I promise. Soon™.

This post is about things. You know, physical objects. Earthly possessions. The indispensable yet fickle chains that bind us to this plane of existence.

As a freshman I loved getting free stuff. I went into my first career fair starry-eyed, taking free pens and t-shirts and sunglasses and drawstring bags from every company that would let me; I’m sure many other MIT students have gone through the same ritual of passing. There seemed to be no downside. Besides, all the swag was probably small change for most of the companies anyway, due to VC funding or massive government contracts or whatever. So I might as well make full use of it.

Less normally (although I have no idea by how much), I also hoarded a lot of things that naturally pop up in everyday life, the stuff that would otherwise get thrown away: extra napkins, plastic bags, produce containers, boxes, those payment envelopes that come with magazine subscriptions and exhort you to Subscribe Now To 12 Issues For 20% Off!! At some point I kept the fortune from every fortune cookie I had ever eaten in a tiny resealable bag. The rationale was basically the same: they might be useful some day¹ and there was no downside.

How to Choose an MIT Username

Thu, 13 Jun 2019 17:39:14 -0400

I wanted to write a post after two years at college about everything I had learned. I didn’t, firstly because I didn’t make it a priority, and secondly because trying to write about everything I’ve learned at MIT over any nontrivial length of time is the kind of poorly scoped endeavor that I could never complete to my own satisfaction.

Two years came and went, and now it’s been two more years and I’ve learned even more things, not to mention, actually graduated. Jeez. I tried to self-impose a deadline for the big post, but it didn’t work out. There were still too many higher priorities, most of which were also natural consequences of graduating. I also couldn’t bring myself to cut anything, because unlike most of the stuff I haphazardly throw onto this blog, I can actually imagine an audience for just about everything I wanted to write about.

Finally I decided that I would break it into lots of small posts on specific topics. This way, at least the perfectionism can’t bleed between posts too much. The first topic I wanted to write about is simple, mundane, and also fairly limited in scope itself: how to choose your MIT username.

refrain

Wed, 27 Mar 2019 18:26:41 -0400

http://111.186.63.17/perf.data.gz

Environment: Ubuntu 16.04+latex

In this challenge, we get a gzipped file called perf.data and a minimal description of an environment. Googling this reveals that perf.data is a record format of the perf tool, a Linux profiler. Installing perf allows us to read perf.data and see some pretty interactive tables of statistics in our terminal describing the profiling results, from which we can see some libraries and addresses being called, but they don’t reveal much about what’s going on. One hacky way to see more of the underlying data in a more human-readable way (and to see just how much of it there is) is perf report -D, which dumps the raw data in an ASCII format, but this is still not that useful. (One might hope that one could simply grep for the flag in this big text dump, but it’s nowhere to be seen.) Still, from this file, we can definitely read off all the exact library versions that the perf record was run against.

Olympiads: The Infinitely Overdue Retrospective

Sun, 03 Feb 2019 16:01:01 -0500

I put this question in my FAQ, because at least two people have asked me this question, and that’s how frequent a question needs to be to be on my FAQ: I got an IMO¹ gold medal in 2012, as a ninth grader, and an IOI gold medal in 2014, as an eleventh grader. I could have kept going to either, or even decided to try taking the IPhO or something, but I didn’t. Why not?

The short answer: It was a rough utilitarian calculation. By continuing, I would probably displace somebody else who would gain more from being on an IMO/IOI team than I would. Besides, I wanted to do other things in high school, so I wasn’t losing much.

I think the short answer actually captures most of my thinking when I made the decision back then, and it’s not really new; I said as much at the end of 2013. But behind it was a lot of complex thoughts and feelings that I’ve been ruminating over and trying to put into words for the better part of a decade. Hence, this post.

There is a natural question that precedes the frequently asked one that I have never been asked, something I am now realizing I never honestly asked myself and never tried to answer deeply: Why did I participate in the IMO and the IOI in the first place?

2019 MIT Mystery Hunt

Thu, 31 Jan 2019 19:39:22 -0500

(this post is sketchily backdated from February 2020)

Fourth year with ✈✈✈ Galactic Trendsetters ✈✈✈. Past: 2018, 2017, 2016, writing with Random in 2015). Evidently I was unable to find the time or motivation to blog about this, and I can’t remember any particularly good stories, so let me just slip this backdated list post in the archives.

The theme in a few sentences: The hunt organizers declare a new Molasses Awareness Day, but because they didn’t follow the proper procedure, throwing the world of Holidays into chaos, where “chaos” means molasses. This resulted in lots of puzzle-to-meta matching, since puzzles were in Holiday towns but metas were at lampposts between two towns.

Highlights of puzzles I solved:

A Good Walk Spoiled (Holi): Happens to be about a topic I know well and find interesting. Fun steps. Justified use of substitution ciphers; the pasting into quipqiup was worth it.
State Machine (President’s): A one-aha! one-step puzzle. Maybe more unfortunate because apparently this was not the only puzzle to use a specific aspect of a specific source material, but I didn’t know about that other puzzle so it’s fine.
Clued Connections (Pi): I went to sleep near the end of this puzzle, so I didn’t see it through, but Floorpi was collectively called out by it.
I Can’t Deal with These Endless Numbers (Patriot’s): Incredible.
Loaded (Arbor): Simple and self-contained enough.

The Prose and the Passion

Mon, 31 Dec 2018 21:05:59 +0800

I was pretty torn between this and “The Future Soon” as the Year-End Song on this blog, but in the end I think I feel more threatened by the bland existence of the soulless adult than inspired by the starry-eyed-idealism-with-misogynist-undertones of the twelve-year-old, plus I get to show you the best kinetic typography video I have ever seen.

Halfway through 2018 I thought this would be the year of ephemeral phases. I felt like I went through a different phase every month — Online Dominion in April, crosswords in June, Only Connect in July, Jonathan Coulton in August, a brief stint of trying really hard to barre my guitar chords in October. Somewhere in the middle, I discovered Kittens Game (“the Dark Souls of Incremental Gaming”) and my summer internship mentor got me to pick up Pokémon Go again. A few intense periods of typographical study were interspersed, which involved watching the above music video dozens of times, teaching a Splash class on typography, and developing a new awareness of how Avenir was everywhere. During the last month, I went hard on Advent of Code and got second place, apparently the only person to make it on every single leaderboard. I also did a related golf side contest and poured a couple more hours into Paradoc, my personal golfing language, for rather unclear gain. At least I got a lot of GitHub followers?

It would turn out, though, that a lot of these phases had more staying power than I expected. Pokémon Go is a much better game than it was two years ago and has actually fostered a significant real-life community, which seems like one of the best possible outcomes of an augmented reality game, and I’ve found a steady pace to play at. I spread the Only Connect bug and people on my hall, intrigued by the format but annoyed by the overwhelmingly British trivia¹, started writing and hosting full games for each other, with our own MIT-slanted set of trivia. One of us developed a custom site and tool to host these games. It took me a while to warm up to Jonathan Coulton’s latest album, but since it happened, I cannot get Ordinary Man or Sunshine out of my head; I’m still listening to JoCo as I finish typing up this post. Although I never got back to the peak of my crossword frenzy, I still study crosswordese from time to time and compose crosswords for some special occasions, like this one (.puz file).

The academics and technical aspects of this year have all blurred together, but I think my interests are finally crystallizing:

React and Redux the Hard FP Way

Fri, 07 Dec 2018 16:44:20 -0500

A more accurate but less informative title for this post would be “How I wish React and Redux were explained to me”. Note that this does not imply that this method of explanation is suitable for anybody else. I suspect it won’t be for most people.

I had to learn React and Redux the past summer for my internship at MemSQL, and there were hundreds of articles that explain React and Redux in addition to the (fine) built-in documentation, but none of them scratched the itch; I wanted to know what was going on completely, including some of the technical details and the philosophy I ought to be following, as well as efficiently. I did not need another explanation about how to think functionally, in JavaScript types or with immutable data. React’s chapter on Conditional Rendering, for example, felt so inefficient — I know what if statements and conditional expressions are, and I know how to refactor complicated subexpressions into variables…

So here’s the guide I wish I had. I think. It’s been months since I started it (as usual, for posts on this blog) and it is probably incomplete. However, I haven’t written React/Redux deeply in a while, so I didn’t have much motivation to continue to investigate the incomplete bits; and the perfect is the enemy of the good, so here it is.

PLC

Sun, 30 Sep 2018 23:16:44 -0400

We’ve burrowed ourselves deep within the facility, gaining access to the programable logic controllers (PLC) that drive their nuclear enrichment centrifuges. Kinetic damage is necessary, we need you to neutralize these machines.

You can access this challenge at https://wargames.ret2.systems/csaw_2018_plc_challenge

A much belated post. This is a pwn challenge on a custom online wargaming platform. We are provided with the assembly of what’s ostensibly a programmable logic controller (PLC) for a centrifuge in a nuclear reactor. The challenge looks like it’s still up, so you can take a look and follow along.

This was the first ROP (okay, spoiler, it’s a ROP) I ever pulled off live during an actual CTF, which I was pretty excited about. The web platform meant I had to worry less about setup, and even though some of the tools it provided were a little lacking (no gdb shortcuts like until, no pwntools utilities for packing/unpacking numbers, … no one_gadget), I think they ultimately made the whole thing a lot more educational for me, so kudos to the folks behind it. I’ve included a brief description of all the exploit techniques that lead up to ROP when we get to that, so hopefully this post will be useful even if you don’t know much about pwning binaries. The prerequisites would be some knowledge with x86 assembly, how executables are loaded into memory, and how to use gdb (or fictionalized web knockoffs thereof).

Proprietary Format

Thu, 28 Jun 2018 23:12:15 -0700

The villains are communicating with their own proprietary file format. Figure out what it is.
$ nc proprietary.ctfcompetition.com 1337

We get a server that will talk to us on a port and a flag.ctf file that’s definitely not a binary. It’s a black-box reversing challenge! I was @-mentioned as the person who might want to due to solving bananaScript (CSAW CTF Quals 2017) as a black box, although that gave a binary that it was possible in theory to reverse. Here black-box reversing is the only option.

For the first few lines of input that the server wants, it responds with quite helpful error messages to help you appease it. If the first line you give it is not P6, it complains:

Cat Chat

Thu, 28 Jun 2018 23:12:06 -0700

You discover this cat enthusiast chat app, but the annoying thing about it is that you’re always banned when you start talking about dogs. Maybe if you would somehow get to know the admin’s password, you could fix that.

This challenge is a simple chat app written in NodeJS. The home page redirects you to a chat room labeled with a random UUID. Anybody can join the same chat room with the URL.

In a chat room, you can chat and issue two commands, /name to set your name and /report to report that somebody is talking about dogs. After anybody in the chat room issues /report, the admin shows up, listens for a while, and bans anybody who mentions the word “dog”.

There are two more commands, /secret and /ban, which are in the server source code and also described in comments in the HTML source if you didn’t notice:

JS Safe 2.0

Thu, 28 Jun 2018 23:12:01 -0700

You stumbled upon someone’s “JS Safe” on the web. It’s a simple HTML file that can store secrets in the browser’s localStorage. This means that you won’t be able to extract any secret from it (the secrets are on the computer of the owner), but it looks like it was hand-crafted to work only with the password of the owner…

The challenge consists of a fancy HTML file with a cute but irrelevant animated cube and some embedded JavaScript.

shellql

Sun, 13 May 2018 15:07:38 -0400

The hardest challenge of not very many I solved in this CTF. What a struggle! I have a long way to improve. It was pretty fun though. (I solved “You Already Know”, and got the essence of “ghettohackers: Throwback”, but didn’t guess the right flag format and believe I was asleep when they released the hint about it.)

The challenge consists of a simple PHP script that opens a MySQL connection and then feeds our input into a custom PHP extension shellme.so.

$link = mysqli_connect('localhost', 'shellql', 'shellql', 'shellql');

if (isset($_POST['shell']))
{
   if (strlen($_POST['shell']) <= 1000)
   {
      echo $_POST['shell'];
      shellme($_POST['shell']);
   }
   exit();
}

The extension basically just executes $_POST['shell'] as shellcode after a strict SECCOMP call, prctl(22, 1). This means that we can only use the four syscalls read, write, and exit, and sigreturn, where the latter two aren’t particularly useful.

Disassembled innermost function of interest in shellme.so

The goal is to read the flag from the open MySQL connection.

Messy Desk

Sun, 06 May 2018 13:52:52 -0400

This challenge is a video of somebody’s messy desk, with what is apparently the audio from a Futurama clip. The desk is indeed extremely messy and full of things that aren’t particularly useful for us, but close examination reveals a QR code reflected in the globe in the middle.

The challenge is all about getting that QR code. After trying our best to clean up the image, we ended up with this:

Maximally enhanced image of the QR code

Pupper/Doggo

Sun, 06 May 2018 13:52:52 -0400

We are presented with a big zip file of SML code, which implements an interpreter for a small ML-like language with a form of taint analysis in its type checker, called Wolf. Concretely, every type in Wolf’s type system has an associated secrecy: it is either “private” or “public”, and in theory, the type system makes it impossible to do any computation on private data to get a public result.

Of course, this is a CTF, so the challenge is all about breaking the theoretical guarantees of the type system. When we submit code, it’s evaluated in a context with a private integer variable flag; our code is typechecked, executed, and printed, but only if its type is public. The goal is to break the type system and write code that produces a public value that depends on flag, so that we can exfiltrate flag itself.

In all, there are three progressively harder Wolf problems, named Pupper, Doggo, and Woofer. Doggo and Woofer are each encrypted with the flag of the challenge before it, so that you need to solve them in order (unless you can somehow blindly exploit servers running SML programs).

Wolf Overview

Let’s first go over the Wolf syntax and semantics. (There are small differences between the three problems, but they’re syntactically identical and only semantically differ in cases that we’ll naturally get to.) The examples folder has some examples of valid code:

let x = (5 :> private int) in
6

On #DeleteFacebook

Mon, 02 Apr 2018 20:09:37 -0400

It feels a little surreal watching #DeleteFacebook.

On one hand, despite how hard it is to keep an issue trending in today’s fast news cycle, this issue has managed to continue burning for a while. Somewhat recently (March 21), we got two high-profile Facebook account deletions from Brian Acton (WhatsApp cofounder) and Elon Musk. Other apparent examples include Playboy and Cher, or see Time or CNET for a few more. Facebook’s U.S. and Canada user base declined for the first time last quarter.

On the other hand, for me and for a lot of people, the scandal just doesn’t seem that qualitatively different from things we’ve known about Facebook for a long time — its stance on privacy, its psychological effects, its willingness to manipulate the user experience. Why is this time different? (Here’s the /r/NoStupidQuestions thread. I don’t actually know which answer I believe the most.)

Is this time really different? I’m not optimistic. The decline could simply be Facebook running out of potential users to add and space to grow. According to a recent Raymond James survey, about half of surveyed users did not plan to change how much they used Facebook, while only 8% would stop using it, and this may still be an overestimate of people who will actually leave or delete their accounts.¹ Mark Zuckerberg himself told the New York Times, “I don’t think we’ve seen a meaningful number of people act on [the #DeleteFacebook campaign]”.

I myself have to admit upfront that, even though I barely use Facebook any more and have carefully contemplated deleting my Facebook account for a long time, I still haven’t pulled the trigger.

Why? What will it take to change this?

2018 MIT Mystery Hunt

Tue, 16 Jan 2018 19:39:22 -0500

My third MIT Mystery Hunt with ✈✈✈ Galactic Trendsetters ✈✈✈ (also see: 2017 and 2016, writing with Random in 2015). It was a good hunt with a fun theme, solid puzzles, and extraordinary production quality, marred only by a fickle unlock structure and a handful of unnecessarily involved extractions.

Since we had been told the hunt would be smaller than past years’ (now a controversial statement since the coin was not found particularly early) and we didn’t particularly want to win (yet), part of our team temporarily split off this year to hunt as Teammate. Based on our Discord channel, ✈✈✈ Galactic Trendsetters ✈✈✈ had 75 people this year, including remote solvers and people who dropped in and out.

A short description of the hunt structure: This year’s hunt theme was Inside Out, the Disney movie about anthropomorphized emotions. This was revealed through a kickoff that demonstrated the hunt’s extraordinary production quality, in which we watched the unveiling of the Health & Safety hunt, first directly, then in the Control Room with the emotions of a distraught hunter (Miss Terry Hunter) and a lot of beautiful memory orbs and scenery. After Terry’s emotions became overwhelmed in response to the theme, we had to help her emotions to allow her to complete the Health & Safety hunt. The intro round took place in the Control Room; we had to solve 34 regular puzzles and five metapuzzles (somewhat overlapping, with some regular puzzles belonging to more than one metapuzzle) to help each of the five emotions get back to the Control Room. The rest of the hunt consisted of recovering memory orbs from each of four Islands of Personality, each of which had its own theme and meta structure, and which we could choose the unlock order of.

Transformation

Sun, 31 Dec 2017 23:59:59 +0800

I think this is the right video for this year.

I love the music and the animation. The music video spells out the central conceit somewhat explicitly, but I think the lyrics by themselves have a hint of ambiguity — is it a harmful addiction that you just can’t escape from, or an essential part of your identity that you just can’t deny?

What parts of me can I just not deny, huh? Unfortunately 2017 is also the year I decide my online presence should probably be a little more professional, so you might have to read between the lines a bit.

Sakura

Sun, 12 Nov 2017 00:00:00 -0500

(Okay, this post is backdated.)

Disassembling the executable produces a huge amount of code. There are some basic obfuscations like a lot of trivial identity functions nested in each other, and a few functions that wrap around identity functions but just add some constant multiple of 16. Most of the meat is in one very large function, though. If you disassemble this function with IDA, you see a lot of variable initializations and then a lot of interesting loops that are quite similar:

Thoroughly Stripped

Sun, 12 Nov 2017 00:00:00 -0500

Woo, first CTF writeup. I got the opportunity to participate in the 2017 CSAW CTF finals with Don’t Hack Alone.

Dumped by my core, left to bleed out bytes on the heap, I was stripped of my dignity… The last thing I could do was to let other programs strip me of my null-bytes just so my memory could live on.

We are provided with a core dump. Examining the flavor-text and the dump, we notice that the dump has no null bytes; we conjecture that they have been stripped out.

Next, we examine the hexdump and look for any clues. There are a bunch of ASCII strings, but they look like normal debugging symbols. One thing that jumps out is that there are a couple fairly convincing regular striped patterns that become vertically aligned if you display 20 bytes in each line. Once we do that, we notice the following section. (This dump is from xxb but xxd -c 20 thoroughlyStripped is quite sufficient.)

Hello, Again

Tue, 07 Nov 2017 00:27:42 -0500

And here we are.

This is the first post on this blog after I migrated off WordPress for a static solution.

At first, I wanted to set things up on Amazon Web Services (AWS), which was an adventure. There are lots of online posts about how to do this, but Amazon’s services change quickly and there was often outdated information. For instance, Amazon had a wizard that led you through setting up a static site, which I clicked on. It helpfully handled a lot of grunt work, but now I was out of sync with all of the guides. Oh well.

I think things are confusing partly because there are four AWS components all interacting to make a static site happen:

Remigration

Sun, 05 Nov 2017 01:56:42 -0500

I guess I lied in my penultimate post.

I’m planning on migrating my primary blog (again), off WordPress to a static site hosted somewhere. I might just throw everything onto GitHub Pages, or might follow any of the zillions of tutorials on how to host static sites off a cheap Amazon S3 bucket — I haven’t decided yet, but no longer having to rely on the free part of freemium services is fairly liberating.

Why? Lots of small reasons.

Me and Facebook

Wed, 27 Sep 2017 15:00:20 +0800

tl;dr: I don’t use Facebook much. If you want to contact me, I would prefer nearly any other mode of communication. I am also going to stop autosharing posts from this blog onto Facebook. RSS readers are great; get yours today.

Recently I checked Facebook and it said something like “You’ve added N friends this past T units of time! Thanks for making the world more connected!” and I just couldn’t any more. Facebook friends are not friends. Dunbar’s number is around 150, maybe double that if you want to stretch it; humans cannot handle that many human relationships. Facebook’s siloed ecosystem is the opposite of connected with the rest of the Internet.

That is one of many reasons I pretty much don’t use Facebook any more. This is not new, but I’ve never formalized it. Also, I figure others might assume otherwise since I still do have an account and still accept friend requests and post sometimes. Thus, I’m writing this post.

Here are all of the reasons:

Taking a Step Back

Wed, 17 May 2017 22:17:26 +0800

There’s some point in the decline of a blog’s activity at which you just can’t apologize with a straight face for not posting any more. Only ironically.

I brainstormed reasons why I’m not blogging. It took a while for me to find a reason that felt right, but I think it’s mostly the concern that I don’t have anything important to say, and I’m just spamming people’s inboxes or Facebook feeds. I make fun of my perfectonist tendencies, but they haven’t gone away and have been exacerbated by how public this blog feels now. There’s also a general feeling permeating life that I should be trying to present myself professionally to people, because like a diamond, the Internet is forever.

I guess January is puzzles month

Sat, 04 Feb 2017 14:27:18 +0800

And it’s not even January any more.

(Thing negative two: Thing zero, which is at the bottom of this post, contains two puzzles by me. Skip there if that sounds interesting and text walls don’t.)

Thing negative one: I abandoned this blog (again). The last month has been a mess and much of it is political stuff of the sort that I’m the worst/slowest at writing about.

Thing one: I was on-site for a second MIT Mystery Hunt.

The More Things Change

Sat, 31 Dec 2016 23:59:00 +0800

It seems to me like lots of people want this year to be over. Among all the other things, 2016 is also apparently the year I totally abandon this blog and put off certain planned posts by several months.

I guess this is what happens when you take five technical classes at MIT. The extracurriculars aren’t helping. And the fastest and most confident writing I do is still reactive, when there’s an externally-imposed deadline or when “somebody is wrong on the internet”. This blog isn’t.

Oh well, time to make up for it in 2017.

What happened this year? I’ll start with some serious categories:

oblig

Mon, 21 Nov 2016 14:53:37 +0800

This is two days late and it’s not even the post that was supposed to be here. That will have to wait until I’m less hosed. ESP just finished running Splash, our largest annual event in which thousands of high school students come to MIT’s campus, and MIT community members (mostly) teach whatever they want to the students. This was the first big program I participated really deeply in as an ESP admin, and it has this way of eating you alive and spitting you out full of joy and immersion in life but devoid of energy and buffer zones for finishing other things by their deadlines.

On a similar note, thanks for all the birthday wishes from everyone everywhere. I’m sorry I haven’t found the time to respond or sometimes reciprocate. This made my day, and probably last couple of weeks too.

It's Complicated

Sat, 12 Nov 2016 12:26:52 +0800

On November 8th, 2016, Donald Trump was elected the 45th President of the United States. Along with a Republican House and Senate majority, to boot.

The world around me is still hurting and reeling from the shock.

Make no mistake, I am scared. I am scared of the policies and executive orders and legal decisions to come that may strip away many civil rights and send the environment down a worse track faster than anyone expected, and I’m barely in any of the groups that have the most to lose. I have no idea what it’s like to go through this as any of you. I am sorry.

But I am also scared that this fear is driving my friends and my community away from talking to the people we need to talk to if we want to make sure this doesn’t happen again.

I’ve heard a lot of people vilify Trump and Trump supporters. Anecdotally, so have others. It’s an understandable reaction, but a fragile one. 60 million people voted for Trump. Quoting Wait But Why, “[P]eople with kids and parents and jobs and dogs and calendars on their wall with piano lessons and doctors appointments and birthday parties written in the squares. Full, three-dimensional people who voted for what they hope will be a better future for themselves and their family.”

People voted for Trump. Why?

Here’s FiveThirtyEight profiling a few blue-collar voters. The Washington Post interviewing an author who spent a lot of time in rural Wisconsin. The New York Times on women. If the articles’ reasons for voting Trump could be summarized in one word, it would certainly be “economy”.

But then FiveThirtyEight tempers it a little bit with this reminder that Trump’s supporters are on average more well-off than others. Here’s The New Yorker visiting a bunch of Trump rallies. SupChina discusses first-generation Chinese immigrants supporting Trump and racism is a bullet point there, but apparently it’s partly rallied around rap lyrics about robbery that advise to “find a Chinese neighborhood” to steal from, so…? I am not going to go any deeper into this rabbit hole. Then here’s Mother Jones arguing against the economy being a big factor at all, and Vox saying it is about racial resentment. Here’s Bloomberg on the Clinton campaign’s failure to persuade and The Federalist on “hyper-liberal late-night comedy” and The Washington Times on Trump’s optimism. I could find hundreds more out there just by Googling, and so could you; and chances are if you’re enough of a voracious reader to be reading my humble blog, you’ve already read some of these.

It’s complicated.

Time, Money, and All That Good Stuff: Part 1 of ∞

Mon, 22 Aug 2016 15:38:29 +0800

I had this 5,000-word draft, but I half-abandoned it for being sappy, boring, pointless, and impossible to rewrite to be satisfactorily un-cringeworthy. Instead, let me just tell you a couple random stories and anecdotes that went somewhere near the start. Maybe posting them will motivate me to salvage something from the 4,500 words that go after it and post it. Eventually.

Some time ago, Namecheap had a discount, so I bought a domain name for 88¢. Unfortunately, the discount only lasted for one year; afterwards, it would cost $29/year to renew. Even though I bought it on a whim and didn’t have much use for it, I found myself wanting to keep it more and more and had a huge mental struggle over whether I could afford it, because wow, $29 is a lot!

Meanwhile, during the same school year, more or less:

Musings on Time Pressure

Mon, 15 Aug 2016 15:44:20 +0800

I hate doing things under time pressure, but I have to admit I do a lot more things when time pressure exists. One of the things is writing. Another is posting the things I write. They aren’t very good, but they’re better than writing that doesn’t exist.

(in case you forgot, I’m still posting this pretty much only because I made myself post once every weekend)

It’s interesting that I can impose time pressure on myself by declaring commitment devices by fiat and it works. Other people have developed other methods of doing this — I recently discovered The Most Dangerous Writing App, which puts time pressure on you to type every five seconds or it deletes everything you wrote. There are many other ways it’s done.

020315040524

Mon, 08 Aug 2016 13:54:22 +0800

--... ---.. ....- ..... ..--- ----- ....- ....- ...-- -.... ...-- -.... ...-- . ....- ....- ..--- ----- ....- ..... ...-- ----. ...-- -.... ....- ...-- ...-- -.... ..... -.... ....- ....- ..--- ----- ...-- ..-. ....- ----- ..--- ----- ...-- ..--- ...-- ..-. ....- ..... ...-- .- ...-- ..... ....- ----- ....- ..... ...-- -.... ..--- ----- ...-- --... ....- ----- ....- ...-- ..--- ----- ...-- ..--- ...-- ..-. ...-- ---.. ....- ....- ....- ..... ..--- ----- ...-- -.. ...-- .- ...-- -.-. ...-- -.... ..--- ----- ...-- --... ...-- .- ...-- ..-. ...-- ..... ...-- .- ...-- ..-. ...-- ---.. ..--- ----- ....- ....- ....- ----- ...-- . ...-- -.... ....- ..... ...-- ----. ...-- .- ...-- ..-. ...-- ---.. ..--- ----- ...-- ....- ....- ----- ....- ----- ...-- -.. ..--- ----- ...-- ..--- ...-- ..-. ...-- ..... ..--- ----- ...-- ..... ....- ----- ....- ---.. ...-- ..-. ..... -.-. ....- ..... ....- ----- ..... -.-. ...-- -.... ...-- ..--- ....- ...-- ....- ..... ...-- ----. ..... -... ..--- ----- ...-- ..--- ...-- ..-. ...-- ..... ..--- ----- ...-- ..... ....- ----- ...-- .- ...-- ..-. ...-- ---.. ..--- ----- ...-- .- ....- ..... ..... -..

..--- ..... ....- ----- ...-- ..... ...-- ..--- ....- .- ..--- ----- --... ---.. ..--- ----- ...-- ..... ...-- .- ...-- ..... ..--- ----- ...-- ..--- ..--- ----- ....- ..... ...-- ----. ...-- .- ...-- ..-. ...-- ---.. ..--- ----- --... ---.. ..--- ----- ....- ---.. ...-- ..--- ...-- ..-. ....- ..... ...-- -.... ...-- ..... ..--- ----- ....- ..... ....- ----- ..--- ----- ...-- ..... ....- ----- ..--- ----- ...-- --... ....- ----- ....- ...-- ..--- ----- ...-- ..--- ..--- ----- ...-- -.. ....- ----- ...-- ..-. ...-- ---.. ..--- ----- ....- ..... ...-- .- ...-- . ...-- -.... -.... ----. ..--- ----- --... ---.. ..--- ----- ...-- ....- ....- ----- ...-- . ....- .---- ...-- .- ...-- -.. ...-- -.... ...-- ..... ..--- ----- ...-- ...-- ...-- ....- ....- ----- ...-- ..... ...-- -.... ....- ----. ..--- ----- ...-- --... ....- ...-- ....- ----- ...-- . ..--- ----- --... --... ...-- ..--- ....- ....- ...-- -.-. ...-- -.... ...-- -.. ...-- -.. ..--- ----- ....- ..... ....- ----- ..--- ----- --... ----. ...-- ..--- ....- --... ...-- ..--- ..--- ....- ...-- ....- ....- ...-- ...-- .- ....- .---- ....- ..... ..--- ----- ....- ....- ....- ----- ..--- ----- ...-- .- ....- ..... ..--- ----- ...-- ....- ....- ----- ....- -.... ...-- -.. ...-- ..... ..--- ----- ....- ...-- ....- -.... ...-- ..-. ..--- ----- ...-- .- ...-- ..-. ..--- ----- ...-- ..--- ...-- ..-. ....- .- ..--- ----- ...-- . ....- ----- ...-- ..... ...-- -.... ....- ...-- ...-- ..-. ..--- ----- ...-- ...-- ....- ...-- ....- ----- ....- ---.. ....- ....- ...-- -.... ....- ...-- ..... -.. ..--- ----- ..--- .- ....- ----- ....- -.... ..--- ----- ...-- ....- ...-- ..--- ...-- ..-. ..--- ----- ....- ..... ....- ...-- ....- .- ..--- ----- ...-- .- ....- ..... ..--- ----- ...-- ----. ...-- -.... ....- ...-- ...-- -.... ..... -----

Pangs

Mon, 01 Aug 2016 15:22:19 +0800

content warning: death, existential dread, the usual

I have this memory —

I was a tiny kid, lying in bed and trying to fall asleep, and I started thinking about death and nonexistence, and I thought about how one day I wouldn’t exist any more, that there wouldn’t be a me thinking my thoughts and perceiving my perspective, and suddenly I was terrified.

I got up and knocked on my parents’ bedroom door and asked them about this. Maybe. Or maybe I didn’t because the fear was less crippling than the social awkwardness of randomly knocking on my parents’ door in the middle of the night to ask them a question like that; I don’t remember. It was a long time ago, okay?

Music II

Mon, 25 Jul 2016 15:50:43 +0800

When I first made myself commit to posting weekly, I was trying to make myself spend a little time every day of the week thinking and writing and whittling away at old drafts. Instead I’m here at 10:40 PM basically starting a brand-new post. Oh well.

I last blogged about music in 2013. I tagged two other posts with “music” since then, but neither is particularly deep: 8 Songs for 18 Years and Drop-In Filler. Let’s continue the tradition of self-analysis part IIs from nowhere…

I meditated a little bit in Conversations about “lacking experience or interest in a lot of the commonly discussed culture.” I think this applies to me and music as well, although not as fully. Back in Taiwan, when mentally bracing myself for coming to the U.S. for college, I sometimes worried about not knowing enough about pop music and bands and not listening enough to popular albums, and having trouble integrating into the culture for this.

Turns out, among the communities I wandered into and friends I made, it was a more frequent obstacle that I didn’t know enough about classical music and composers. Whoops. Some of the names rang faint bells from either music class or conversations with high school friends who did do classical music, but I could not identify or remember any styles or eras, and would remember composers only by unreliable first letters or unusual substrings of their names.

Gaming

Mon, 18 Jul 2016 16:55:32 +0800

It’s another weekend, isn’t it.

I’m out of deep things to say. I don’t usually have deep things to say. Sorry to anybody who subscribed hoping for more things like the last post. This is basically going to be a personal stream of consciousness post. But it’s a stream with a long ancestry, since I apparently wrote 400 words about it in a WordPress draft four years ago. This was way back before I even started writing post drafts in Markdown on my computer instead of directly in WordPress, so I guess it must be an interesting topic.

Four years ago, Brian₂₀₁₂ was suddenly struck by how many of the people he knew were such serious gamers. But let’s go back even earlier, shall we?

A long long time ago, when I was in elementary school or so, my parents had some sort of reward system where I had to do productive things, like study or do chores or write diary entries or practice the piano or something, to earn time on the computer for games. “Gaming time” was a currency. I enjoyed saving up lots of thirty-minute increments and knowing I had the freedom to using them slowly.

That much I remember; the details of how it worked are very fuzzy and I’m not sure what I played in those thirty-minute increments either. I think there was Neopets and Runescape and Club Penguin. (My Neopets account still sees sporadic activity, because I get really really bored sometimes…)

On Islam, Headlines, and Definitions

Mon, 11 Jul 2016 15:29:43 +0800

This post’s topic might be the most controversial thing I’ve posted here ever. I hope the points I want to make aren’t.

One of the excuses for not blogging I came up with and then deleted while rambling about not blogging was that I’m getting more feelings about real-world real-person issues, things that people take heated positions on — it’s not topics like what food I ate or what games I’m playing in fourth grade any more — and my identity is pretty public here, so who knows what’ll happen. Oh well. I’m probably just paranoid.

It’s also delayed, as the articles I’m talking about are old; the latest two news items are the shootings of Alton Sterling and Philando Castile and then the police shooting at the Dallas rally. That was also really sad, but I don’t think I have anything insightful to say about it. Let me point you to the MIT Admissions post, “Black Lives Matter”, and then for something a bit more optimistic out of a huge range of possible choices, this Medium article.

Although after I started writing this post, the story about a Muslim man preventing an ISIS suicide bomber came out, so now this is mildly relevant again. Anyway, I guess the delay is no different from how I put up life posts weeks after the life event happens. So today, I bring you two old news articles about Islam that my friends shared and discussed:

The second one first, whose argument is, to be frank, weak. I think this piece from The Atlantic by Wood, “What ISIS Really Wants”, is a better-researched overview of ISIS while still being pretty readable. One caveat is that it’s somewhat old. But its central claim is quite the opposite:

Conversations

Mon, 04 Jul 2016 13:10:21 +0800

One of the most unexpectedly different facets of life during my internship has been the meals.

I’m not talking about the food; it’s certainly different in a fantastic way (Dropbox’s food (link to Facebook page) is like something out of a high-end restaurant), but I knew that before coming already. Also of note is the way I started eating ∞% more ramen over the weekends than I did over the entire school year at MIT, because here I can’t buy that many groceries without them spoiling and am amazingly lazy in this new environment.

No, this (deadlined, so not that well-thought-out, but whatever) post is about conversations at meals, which happen basically every lunch and some dinners when my team eats together.

I’ve never had any regular experience like it. Of course I’ve had many meals at home with family, but they feel different because, well, it’s family and we have so many topics in common. I went to the same school for twelve years and we didn’t generally use a cafeteria; we just ate at our desks in our classrooms, or while doing things like attending club meetings or taking makeup tests. Sometimes if people felt like it they would push desks together to eat, but eating by oneself was totally normal. (At last, I feel like that was what it was. It seems so far away now that I don’t trust my memory, which is pretty sad… I faintly suspect I would have this experience in a more stereotypical American high school. But this is mostly just based off the cafeteria in Mean Girls, a movie I only watched in its entirety on the flight here, which is weird because I know I’ve seen the “The limit does not exist!” part much much earlier. /aside)

And at MIT? “Time is an illusion. Lunchtime doubly so.”

I am glad for these conversations over lunch because I get to know my team more personally (and don’t have to awkwardly eat alone in the bathroom), but they’ve also given me a lot of time to ponder my (lack of) conversation skills.

No Excuses

Mon, 27 Jun 2016 14:08:54 +0800

Wow, this has been the longest silence on this blog in a long time.

I can’t justify it with lack of time either. Interning at Dropbox takes up all of my weekdays, but my weekends are much freer than I’m used to. I carelessly let two weeks at home in Taiwan pass by without doing much about blogging, and once again a lot of my few blog drafts have drifted into the temporally awkward zone, being too far away from the events they are about.

Neither is it for lack of things happening. At MIT, there was the Senior House turnaround and freshman moratorium. I can’t even begin to sum up the discussion around this issue, but I think the best response I’ve read is this open letter. Then there’s the official Senior House response. But that’s enough links, since I imagine the chances that this issue is relevant to you and you’d need this blog to link you to them if you’re reading this are pretty low. (Then again, the chances that you’re reading this are already pretty low. Although the chances you are reading this right now is 100%.)

[insert name here]

Wed, 23 Mar 2016 15:31:22 +0800

(I’m making random short posts to entertain certain people during spring break.)

Since air-dropping into this crazy cultural salad bowl of a place, I’ve met a lot of people whose names get mispronounced. All sorts of long vowels and short vowels and consonants and word boundaries that jump across languages unpredictably. As a result, people often acquire nicknames or alternative names to get called by, whether actively, passively, or somewhere in between.

In contrast, my name is easy and boring. Now, I rather doubt I’d want an exciting name, in the sense of a name that everybody mangles in excitingly different ways. I’m not exactly dissatisfied with people calling me “Brian”. It just strikes me that I think I’ve gone my entire life without a meaningful nickname or even meaningful derivative of my name.

(I’m ignoring the transposition. Why am I ignoring the transposition? I’m not sure I can rationally justify that, but thinking about it makes me cringe, which is the reason I’m delicately avoiding explicitly writing out what nickname I refer to by “transposition”. I will just say it is rather uninspired… and also, perplexingly to me, used by accident a lot…)

Zootopia

Mon, 21 Mar 2016 14:27:21 +0800

(So. It’s spring break. Two-week-late post, and somehow by the end it’s all aboard the angst train again?)

Two Sundays ago, I mobbed with a small group of MIT furries to watch Zootopia, the recent highly-reputed Disney movie.

(Before anything else, first there were the previews. I was impressed that every single one of them — there were six or so — was about an upcoming movie featuring anthropomorphic animals front and center. Let me see if I can remember all of them… in no particular order, Teenage Mutant Ninja Turtles, The Secret Life of Pets, The Jungle Book, Storks, Finding Dory, and Ice Age: Collision Course. edit: Oh, also Angry Birds. Wow, I said, they know their audience.)

I went into the movie with a vague impression that Zootopia was more adult-oriented than most Disney films — not in the naughty way, but in general making a lot of jokes and invoking a lot of parallels that I think only adults might have the experience to get. My suspicions were confirmed a few lines into the movie, where there was a joke about taxes I cracked up at but can’t imagine that children a few years younger would have found funny. If you the reader haven’t watched it, I hope that was vague enough not to ruin the start for you.

(To be fair — and, uh, some parts of the internet are kind of big on this fact — the film also at one point enters a nudist colony. Fortunately (?), Animals Lack Attributes.)

Humor aside, I think the movie also deals with some weighty and nuanced themes, ones that would take more life experience to fully appreciate than the themes of most Disney movies. The social commentary is very clear. Possibly bordering on too blatant for my tastes — even though the whole movie is kind of Funny Talking Animals, there are some animal species for which it’s really easy to guess which human demographic groups they might be symbolizing, to the point where I can already imagine the other side of the debate. You won’t need a PhD in literature to figure out the parallels; you wouldn’t even need an AP English Literature class. But, I think, it still works. It’s like Animal Farm on training wheels.

Brand New

Wed, 03 Feb 2016 14:26:13 +0800

(all the times that you beat me unconscious I forgive)

angst [████████ ] (8/10)

We’re overdue for one of these posts, I guess.

(all the crimes incomplete – listen, honestly I’ll live)

Last-ditch feeble attempts at cleaning and reorganizing my desk and shelf before I figuratively drowned in academics led to me finding

the Google physical linked puzzle, which I placed in the Kitchen Lounge to nerd-snipe people, successfully
a Burger King crown from the previous career fair
ID stickers from the Putnam, one of which is now on my keyboard cover cover (← not a typo), just because
assorted edibles, like candies and jellies, which I ate; as well as the half-finished Ziploc bag of candy from my FPOP, six months ago, which I just tossed in the trash
a box. It’s just, like, a box. I don’t know what goes or went into it

I feel more in control of my living quarters. Marginally. Guess I’ll be fine.

(mr. cool, mr. right, mr. know-it-all is through)

Pros and cons of having a departmental advisor in your area of interest:

Pro: the advisor knows something about the classes you want to take and can help you choose classes
Con: the advisor knows something about the classes you want to take and can help you choose classes

whoosh

Mon, 01 Feb 2016 08:19:46 +0800

I finally did it.

I was on-site for the 2016 MIT Mystery Hunt. I even solved a metapuzzle. This year I hunted with ✈✈✈ Galactic Trendsetters ✈✈✈, the team primarily but not overwhelmingly formed from floorpi, my dorm floor. (Perhaps somewhat regrettably, I didn’t contribute to any events or runarounds or things given to HQ, unless you count attending a “recitation” for Student Simulator (round King Arthur, second from left).)

(Also, I made this post. Has it been two weeks already? Okay, that’s not an unusual timeframe.)

But wow, I got to touch so many puzzles.

Non-spoilery comments on particularly memorable puzzles I did, which are disproportionately programming-related, if anybody wants to look at them (I am describing how to get to the puzzle from the round instead of linking because I’m lazy and links might rot but the instructions will hopefully survive archival (although turns out there’s actually a table of contents so I don’t know what I’m doing)):

Ascension

Thu, 31 Dec 2015 23:57:31 +0800

I wasn’t sure what would be the right song for 2015 until I set foot on MIT. Then it was a no-brainer.

Where do I even begin?

I thought cooking was hard. Then I ended up in the kitchen on the third floor of the west parallel of East Campus and had to produce something edible. So I figured out how to acquire chicken and put it in a pan with some onions and heat the whole thing up. It wasn’t even that bad! A few weeks later, I graduated to cooking in a rotation for six people. All this from a guy whose culinary abilities only went as far as frying eggs a few months ago. It’s incredible where life takes you sometimes.
I thought I couldn’t productively listen to lyrical music while doing homework, because I get distracted and/or bogged down by the feels. Turns out there’s a category of metal songs with great atmosphere and terrible lyrics that does the trick.
I had planned to suffer through introductory chemistry my freshman fall and introductory biology my freshman spring, and thereafter be done with required classes. Well, I took chemistry, but there was barely any suffering involved, and now biology fits nowhere on my freshman spring schedule.
I had some outlandish hopes I’d walk into college and be able to become mildly financially independent because people would throw high-paying jobs at me that I could learn from, but I didn’t expect it to happen. Life isn’t that easy!
Well… it happened.
An incredible number of redacted things.

I’ve never been that kind of guy. Honest and innocent to a fault, no secrets except those arising from paranoid self-assigned concern about others’ privacy: that’s me. Until this year.

Oh well, I can’t blog about it.
[redacted]
But mostly, of course, I actually graduated. The teacher-appreciation dinner happened (6/4), where I debuted my graduation song (woo!) and ate some good cake (double woo!); senior prom happened (6/7), with some awesome photos; and then, actually, the graduation ceremony. (6/10, same day I realized I had recently passed 100 starred things on GitHub.)

::looks at self:: I’m actually a college student now.

Every one of these stages of life seems like it should be a big deal, like I should pass through and suddenly know all the things about maturity and aspirations and life that are expected of college students, but it never happens that way.
At least, all things considered, I think this transition was very successful at taking my mind off the angsty side of things. This post is actually surprisingly unangsty. Sorry to disappoint if that’s what you’re here for!

Puzzle 49 / Triple Back

Wed, 23 Dec 2015 00:25:46 +0800

I’m not really satisfied with the execution, but eh, what the hell. My brain can only function at so much of its full capacity when it’s a few kilometers up in the sky.

This is a Triple Back, variant on MellowMelon’s Double Back. Briefly, draw a closed loop through all square centers visiting each bold-outlined area exactly three (= ⌊π⌋) times. Shaded cells do not influence solving, only aesthetics.

November 2015 Puzzles Hints

Sat, 21 Nov 2015 13:16:59 +0800

A Signature Puzzle: Trying to solve the puzzle with Extreme Speed can’t hurt. Anticron: This puzzle runs on two distinct 24-hour clocks, which is why you can be zoned out for half the time and still solve it. When Is My Birthday Again?: Apparently, if you don’t want to tell your friends your birthday, you can tell one of them the month and the other the day. And if you really want to annoy them, you can change one of the days at the end so they have to work it out again.

Three for the Price of One (Meta)

Fri, 20 Nov 2015 13:00:00 +0800

And that’s another year!

As usual, you can check your answers here. Text above this horizontal rule is not part of the puzzle.

Solvers:

Yoshiap @ 11-20 13:31:56

When Is My Birthday Again?

Thu, 19 Nov 2015 13:00:25 +0800

As usual, you can check your answers here. Text above this horizontal rule is not part of the puzzle.

Solvers (in my local UTC−5 because I’m lazy):

Lewis Chen (phenomist) @ 11-19 05:03:07
Jack Lance @ 11-19 10:39:11
Yoshiap @ 11-20 03:29:54

Anticron

Wed, 18 Nov 2015 13:00:59 +0800

Unfortunately, I did not get this successfully testsolved, although, for whatever comfort it may provide, I did engage in several interactive rounds of nerfing it.

As usual, you can check your answers here. Text above this horizontal rule is not part of the puzzle.

Solvers:

A Signature Puzzle

Tue, 17 Nov 2015 13:00:06 +0800

As usual, there had to be something here. In fact, this year, there are several somethings. Hype!

This is based on an idea by chaotic_iak. You can check your answers here. Text above this horizontal rule is not part of the puzzle.

ETA 11/17 16:15 UTC−5: Adjusted spacing between the bottom numbers after feedback. The puzzle is otherwise the same, and solving should not be significantly impacted.

Solvers (in my local UTC−5 because I’m lazy):

Yoshiap @ 11-17 18:28:34

Pause

Fri, 13 Nov 2015 16:03:56 +0800

There are 30 minutes until my laundry finishes.

It is 2:30 in the morning as I write this. Normal people are not awake at this time of day. It’s possible that normal MIT students are, though.

I’ve been meaning to blog for a while, but things happen and other things happen and still more things happen. From a state of total inexperience in the kitchen, I’ve already managed to single-handedly cook six six-person meals for my co-op, not to mention all the weird meals I make for myself (which is just as well, I don’t think they are of typically mentionable caliber.) I’ve already taken two exams in three of my classes and the big midterm for my fourth. Four puzzlehunts — Simmons, aquarium, Palantir, ΣUMS; five if you perhaps include Next Haunt. Six SIPB meetings. A few bottles of Soylent; I lost count and don’t want to check my room because that’ll disturb my roommate. Θ(3000) zephyrs. And after many weekends of eye-opening group practice, tonight I have to catch a flight to Rochester, NY for ACM-ICPC regionals.

Sharpies

Sun, 08 Nov 2015 14:59:48 +0800

As readers of this blog probably know, I am not an MITAdmissions blogger. It was kind of disappointing at the moment, but now I rarely think about it except when I come up with good reasons why I shouldn’t be an MITAdmissions blogger. One reason is that I am not very good at coming up with advice that could generalize to a wide audience, even an audience only as wide as people at or coming to the ‘Tvte. (There can be only one!) This by itself probably wouldn’t be so bad because there’s plenty of generalizable advice to go around, but I also don’t like repeating well-known stuff. Don’t skip class, except when you really know when you’re doing, which you probably think you do when you skip class. Get enough sleep, maintain good study habits, set aside time to keep up with old friends, back up your zarking data, alternate alcoholic and nonalcoholic drinks, do not forget the factor of one-half when computing the area of a triangle. You get the picture.

There’s only one piece of advice I can say that I believe is generalizable to any degree, and in particular I think my past self would have appreciated and also had not heard, even in passing, from any other source: Get a Sharpie.

Carpe Annum

Fri, 02 Oct 2015 14:47:00 +0800

A fun/interesting/unfortunate/fortunate consequence of the mental world model of Inside Out (2015 Pixar film) (which is a great movie, and I’m saying this as a non-movie-type — I laughed, and I cried, and just omgwtfbbq Disney/Pixar) is that imaginary friends that are capable of autonomous flight are probably immune to being forgotten.

Unfiltering

Thu, 24 Sep 2015 14:00:18 +0800

People are afraid of the dark because it holds the unknown and unknowns are scary. But maybe it is just as frightening if we let the light shine everywhere and believe that because we know everything the light shines on we know everything. Perhaps for once when the sun fades over the horizon and the darkness returns in its dependable cycle we should silence the fears and remember there is darkness in all of us

Jam-Packed Fun and Games

Mon, 21 Sep 2015 00:45:43 +0800

Did I say “fun”? That was short for function calls. Which are fun too, admittedly. Blah, I always go to such lengths to come up with snappy yet justified post titles and end up achieving neither.

One more complimentary breakfast later:

This is it.

Google Code Jam World Finals. Let me take a moment to reflect. Seriously. I do not know how I made it this far this year. I guess I might be a top-500-ish competitive programmer globally, maybe even top-150-ish, but definitely not top-25-ish. And Log Set, the hard problem that got me through Round 3, doesn’t seem like it plays to my forte particularly either. It’s a bit mathy, but the math bits aren’t the hard part; I think it’s largely implementation, with one psychological hurdle where you have to realize that, because of how few distinct integers there are in S′, you can efficiently solve the subset-sum instances you need to produce the lexicographically earliest answer. I’m actually kind of impressed I got that. It seems like the sort of hurdle I usually get stuck on. How did this happen?

Maybe randomness. Maybe I was just particularly clear-minded during the round and wrote less buggy code than usual, because I had no expectation of making it whatsoever and so could look at the contest detachedly (until midway through the contest I accidentally noticed that my rank was under 20, and even then I tried very very hard not to think about it, and it kind of worked).

But it happened, and now I’m here. Time to roll.

In some emails much earlier in the Code Jam logistical process, Google had asked for “requests for changes and/or additions” to the software that would be installed on our competition computers, and I had sent them a long list:

Hi,
Here are some things I’d like if they were installed, in decreasing order of priority:

The Vim plugin syntastic ( https://github.com/scrooloose/syntastic )

a Haskell compiler (probably Haskell Platform 2014.2.0.0 https://www.haskell.org/platform/ even though it’s a year old)

the Haskell package hdevtools ( https://hackage.haskell.org/package/hdevtools ) so that the above two may be integrated

(I don’t have enough Linux experience to name a specific thing to install, but command-line utilities that are the equivalent of pbcopy and pbpaste on Mac OS X, which allow me to redirect text into or out of the clipboard from the command line easily)

Of course, this is my first Code Jam and I don’t know how reasonable these requests are. Any nontrivial subset would be appreciated.

Orthogonal Planes

Sun, 20 Sep 2015 11:13:14 +0800

I have a backlog of at least 6,000 words and still too many events to blog about, so these posts will not reflect things currently happening to me for a long, long time, except for the little blurbs on top of posts like this one when they exist.

Blogging is hard.

Also, I don’t have a good title.

It begins with an airplane.

For Zarquon’s sake, you’re entrusting me with my own passport and airline tickets and luggage and all this stuff I can’t even. I still layover people for months on end in Pocket Planes sometimes. (Watch the graceful descent of this reference into personally overused snowclone territory.)

Source: Taiwan, my home for the previous twelve years, which I am now bidding farewell to for the longest time in forever (…which is only (“only”?) five months, assuming I fly back for winter break as already planned). Destination: Seattle, for this year’s Google Code Jam World Finals, which I still don’t know how I managed to qualify for (more on that in later posts); and, before that, an accompanying interview for an internship that I scored as part of the bargain.

I successfully get on the plane, sort some nice things to have on hand into my MIT tote bag (how did I ever survive airplanes without keeping a tote bag on hand?), and put my backpack with the rest of my stuff into the overhead compartment. An old-ish guy who is probably Korean sits next to me. Plane takeoff is a bit delayed due to traffic congestion. Once during the flight, after an attendant passes out forms to everybody entering South Korea and I tell him I’m not, the guy asks me where I’m going and we have a short conversation. But for the most part, it’s typical airplane shenanigans. I listen to Avril Lavigne and Ellie Goulding, do a little homework, and eat the airplane food. Nothing remarkable happens.

Until near the end of the flight: a guy in a suit shows up in the aisle and, looking at some sort of checklist, calls my name.

Puzzle 48 / Double Back

Sun, 06 Sep 2015 23:15:44 +0800

At least one person wants me to post. I’m not even going to try do a life summary. It’s too hard. Let’s just say:

right now, my blog drafts contain a backlog of ~7500 words and counting;
I was not accepted as an MIT Admissions blogger, which is bad because my blogging will continue to not reach a large audience, but good because my blogging will continue to not reach a large audience. Maybe it had something to do with the fact that, because the application form wouldn’t let me submit without any media, I panickedly cranked out the following puzzle in an hour or so to attach.

Glowstick Fragments

Wed, 12 Aug 2015 09:34:22 +0800

Echoes.

On the HSR we kill time with weird games from Kevan Davis’s Freeze-Dried Games Pack, mostly Thirty-One. Then we’re there!

On the bus we kill time with karaoke, until people complain. Sorry.

Lunch at Chinese restaurant. Beach resort.

I spend the first one and a half hours holed up in my hotel room watching television, first a quiz show where the host asks foreigners living in Taiwan questions about the country’s culture and society, then Disney and Cartoon Network cartoons. During the commercial breaks I do cryptic crosswords I had brought along. This is something I self-deprecatingly talk about for the rest of the trip, but I have no regrets because the three cartoons I watch are literally my top three guilty pleasure cartoons, Ben 10, Teen Titans Go!, and Jake Long: American Dragon.

Then I wander around and join some guys playing pool. I do better than I expect, once pocketing three balls in sequential moves. There is also a Kinect with a dancing game, which I also score surprisingly well at and have lots of fun playing.

Dinner, in which I eat 小卷 (“pencil squids”?) with way way way too much wasabi. I stuff myself and walk around chatting and eventually learn there are freshly-made 手卷 (“temaki” / “hand roll”) downstairs. Since there’s lots of time I wait until I’m less full and eat two.

Group activity outside corresponds eerily to the one three years ago: shouting, dancing, waving glowsticks, arbitrary dance moves, punishment games, cooperation games, a competition where the guide gives out points that don’t matter like on Whose Line Is It Anyway?

Empty promises… but okay. Class songs. (This is the explicit version. This song is well above the normal offensiveness rating of this blog and I usually prefer official videos, instead of shady lyric videos probably made from Windows Movie Maker that might get taken down, but honestly I find the pathetic execution of censorship in the VEVO version more offensive.)

edit from the future: There used to be an explicit YouTube video of Shots by LMFAO ft. Lil Jon here, which has since been taken down for obvious reasons. Yes, it is a very crude song. I never went to a party that was a tenth as wild as the song describes. Maybe it was my means of vicarious escape.

After it we have a sentimental moment listening to “See You Again”.

At night our room flips through television and watches the second half of Iron Man 2.

[CIMC 2015 Part 3] Monsters and Pandas and Tigers, Oh My!

Tue, 11 Aug 2015 23:32:37 +0800

My inner perfectionist is crying that I have to post this, in particular over my pathetic snowclone title, but my inner pragmatist knows that, judging by my old blogging patterns, it’s now or never.

18.06: 56%, haven’t touched it in a while, but I think I can do lots more on the plane.

As a non-contestant, I confess I feel totally uninvested in the results and find the Closing Ceremony boring. All contestants go up, country by country, and have their awards read off. No effort is made to make any sort of buildup to a climax. But maybe this is for the best; we don’t want anybody feeling shafted or discouraged from continuing to do math due to a mere elementary-/middle-school competition. Meanwhile, though, I’m browsing reddit on my phone.

After this ceremony, the entire Taiwan delegation spends some time walking around outside while the guides make confused phone calls trying to decide where we eat lunch. My parents offer me some potato chips they bought somewhere, which are (as the label is really eager to point out) baked, not fried. Some time passes this way; eventually, the guides figure it out and we go through amazingly long queues to eat at the cafeteria, as usual. Then we are sent to a massive shopping mall for the afternoon, a place so large that its exits have number labels that go up into the double digits so that people don’t get lost.

I take trippy failed panorama photos from the bus windows.

[CIMC 2015 Part 2] Journey of the Blue-White Slippers

Fri, 07 Aug 2015 12:04:30 +0800

(Nontopical life update: Current 18.06 homework status: 34% (mildly screwed, probably won’t finish before I leave my cozy home for the U.S. and I usually struggle to get into the mood for homework while traveling, but I guess I’ll have to)) (I’ve been spending most of my uptime doing said homework and running errands, and my downtime catching up on Last Week Tonight with John Oliver while farming the Flight Rising Coliseum. And, okay, making the above status panel. Live version here courtesy of Dropbox’s Public folder. No regrets.)

Day 3 (Excursions)

Morning routine snipped. We come to the middle school again to eat breakfast and gather; the contestants will be taking their tests here (accompanied by one bottle of “Buff” energy drink each) while the rest of us will be going on an excursion. Before this happens, though, two Taiwanese contestants ask me and Hsin-Po some math problems. There’s a geometry problem, which I fail to solve:

(paraphrased) In triangle △ABC, ∠A is 40° and ∠B is 60°. The angle bisector of ∠A meets BC at D; E is on AB such that ∠ADE is 30°. Find ∠DEC.

Hsin-Po figures out that, once you guess (ROT13) gur bgure boivbhf privna vf nyfb na natyr ovfrpgbe naq gurl vagrefrpg ng gur vapragre, lbh pna cebir vg ol pbafgehpgvat gur vapragre naq fubjvat sebz gur tvira natyr gung gurl vaqrrq pbvapvqr.¹ Then, there’s a combinatorics problem in a book with a solution that they’re not sure about:

[CIMC 2015 Part 1] Rainy Days in July (and Other Months)

Tue, 04 Aug 2015 13:48:45 +0800

We get up at 3:40 AM. By 4 AM we have left our house, speeding like a bullet into the dark.

(Ohai. Somehow it slipped my mind that I was ending my streak by leaving the country for a competition that would likely be highly bloggable, like my last two international olympiads, both of which led to notable post sequences on this blog. (Admittedly, the first one was never really completed…) My only excuse was that I was worried I might not be able to access my blog from inside the Great Firewall, but I did (via vpn.mit.edu) and even if I hadn’t, I could still have drafted posts locally in Markdown as I usually do, so I don’t know what I was thinking.)

(Also: because, as I’ve said way too many times recently, I need to do linear algebra homework, these posts aren’t going to be as complete or as perfect as I’d like them to be. Although I’m probably just saying this to persuade myself; I tend to include many of the boring parts as well as the interesting parts of the trip, which maybe benefits my future self at the expense of other readers. I probably need to get out of this habit more if I want to blog for a wider audience, though. Oh well.)

Backstory

The International Mathematics Competition (IMC) is, as it says, an international mathematics competition. But I should add that it is for elementary and middle-school students (in other words, I am not competing, okay??). (edit: Also, one or two letters are often prefixed to indicate the host country, for whatever reason. This year it would be CIMC, C for China.) I am tagging along because I am a student of Dr. Sun, one of the chief organizers, and have been slotted to give a talk and possibly help with grading the papers and translating. My father is coming to help arrange a side event, a domino puzzle game competition, which he programmed the system for; and my mom and sister are also coming to help with translation and other duties. Other people in our group: Dr. Sun himself, his longtime assistant slash fellow teacher Mr. Li (wow I’m sorry I forgot you while first writing this), my friend and fellow math student Hsin-Po, who is an expert at making polyhedra from origami or binder clips (and at Deemo); Chin-Ling, my father’s student/employee who also programmed lots of the domino puzzle server and possesses a professional camera; and, of course, all the elementary- and middle-school contestants, as well as most of their parents.

I don’t think I’ve ever given this amount of background exposition about any event I’ve attended to my not-so-imaginary audience before. It feels weird. Some part of me is worried about breaking these people’s privacy by posting this, which makes a little bit of sense but not enough for me to think that it’s actually a valid reason to avoid or procrastinate blogging. I think it’s a rationalization.

Here we go.

Day 1

The only interesting thing that happens at the airport is a short loud argument in the queues for luggage check-in, perhaps partly fueled by our high number of people and of heavy boxes (gifts for other countries and raw materials for Hsin-Po’s polyhedra). I don’t know whose fault it is.

In case I fail to scale the firewall, I attempt to download Facebook on my phone for one last look before boarding, but it fails during installation twice and I give up.

Our plane is not fancy enough to offer personal screens and entertainment centers for everybody, but thankfully the ride lasts only three hours, so this is tolerable. Instead, the plane plays the second Divergence movie on overhead screens, which I watch half-heartedly. The plot setup seems interesting but the ending seems to me to involve two Ass Pulls™, although since I haven’t been paying much attention I am not confident if I just missed some foreshadowing or character development. On the flight, I also read the proof of the irrationality of powers of e in Proofs from THE BOOK and leaf through the magazines.

I don’t hear any good music on-board, except maybe “Space Oddity”, which is a little freaky to be listening to while cruising at so may kilometers in the sky. Perhaps because of this, I find myself singing and humming “Space Oddity” unexpectedly often over the next few days.

Arrival

The very first sign we see after alighting the plane consists entirely of characters that are the same in Simplified and Traditional Chinese — if I remember correctly, 「前有坡道，小心慢走」¹. The Changchun airport looks like any other airport, coolly blue-themed with moving platforms. The restrooms have fancy bright purple soap. Even though I consciously think about how I have suddenly arrived in a country that places notable restrictions on freedom of speech and Internet access, I don’t feel it. Eep, what an anticlimax.

C-c-c-Combo Breaker!

Mon, 27 Jul 2015 07:10:20 +0800

I made it!

After a misstep on the fourth day I managed to post one post every day, completing the rest of the streak! This post is scheduled to go out around the time my plane takes off.

I’m free!

I’d insert a Frozen gif here if I could find a good one, but I don’t like any of the ones I found and besides, copyright is an issue. So instead:

source: Wikimedia Commons, public domain

IMO2007.C6. In a mathematical competition some competitors are friends. Friendship is always mutual. Call a group of competitors a clique if each two of them are friends. (In particular, any group of fewer than two competitiors is a clique.) The number of members of a clique is called its size.

Given that, in this competition, the largest size of a clique is even, prove that the competitors can be arranged into two rooms such that the largest size of a clique contained in one room is the same as the largest size of a clique contained in the other room.
Author: Vasily Astakhov, Russia

If you remember where I first posted this to break a combo, you have an excellent memory and/or spend too much time stalking me. If you remember the context under which I posted this to break a combo, you have a better memory than I do.

Was my streak a success? On the bright side, I definitely generated lots of posts, many of which were radical departures from my old blogging habits:

card game documentation,
weird short stories and sequels to weird short stories,
an essay (liberally defined) with two parts,
an essay with two parts and a half,
another bar graph that is actually documented,
a ridiculous literate Haskell post,
numerous facetious Paintbrush dragons,
a post about a post on a side blog,
and, of course, metric zarktons of shameless filler.

I also had lots of fun conversations about my posts, such as:

[warp]clicker.html

Sun, 26 Jul 2015 11:46:04 +0800

Okay, just one more post for the streak milking the stuff uncovered in my old hard drive, and then it’s over, I promise. Here is a silly three-button idle game I discovered, which I apparently made in 2010 when I was a bored eighth-grader and the most recent jQuery version was 1.4.x. Instead of enjoying a text wall, please enjoy trying to get 16,384 clicks in the non-warp version. (There’s no victory message or anything; it’s just a nice round number that I reached while writing this post. And yes, I know you can call JavaScript from your developer console, or edit the source or DOM. That’s cheating.)

And I realize this is short even for filler posts, so if you don’t want to play an idle game, here is a remix of numbers.bmp to stare at and feel inspired by. Or disgusted with, or indignant at. Your choice.

Old Tests (and a Mysterious New Student)

Sat, 25 Jul 2015 23:57:41 +0800

(Short streak post. And for the uninformed, I’m using Spivak pronouns for this post just because.)

Generally, when people I don’t already know through math competitions ask me or my parents about something like how to teach their intelligent child to make em really good at math, or even English or whatever, I am skeptical by default because there seem to be a lot of Taiwanese parents who have alarmingly rigid and largely baseless expectations or assumptions about what their children ought to be interested in and excel at.

You can lead a horse to water, and honestly I think you could find a way to force it to drink if you really wanted to, but you can’t make it enjoy the process of being force-fed. Um. Force-watered? Force-hydrated?

You can teach your child math and English, and you could make em ace all eir tests, but you probably can’t make em enjoy the test so much that e decides to create more diabolical versions of these tests to give to eir fictional characters in eir stories for fun!

These are all actual illustrations from the old stories I mentioned in part 2.5 of “More Fiction”. Stories I wrote in 2004. As a first-grader.

This is kind of horrifying.

More Fiction (Part 2.5)

Fri, 24 Jul 2015 20:27:44 +0800

This is not Part 3. It’s just two things I thought of tacking on to part 2.

What can I say? Part 2s are easy blog post fodder; Part 2 appendixes are even easier.

One, there’s one other wall I run into often during those rare attempts when I get motivated enough to try to write a story: naming characters is hard. At least, it provides an excellent motivational roadblock whenever I even consider committing a story to paper, a point before I’ve actually written anything at which I think “maybe I should give up and go on Facebook instead” and proceed to do so. Aggh. And I think there’s more than one reason for this:
- I have trouble coming up with names to some degree. Sure, it’s easy to browse BabyNames.com and look for choices, but a lot of the names there are really weird and contemplating them for every unimportant character kind of rips me out of the immersed mindset.
- Reading great stories in English class and elsewhere may have gotten me feeling like every name ought to be a deep meaningful allusion, or at least pun fodder. I feel like I will regret it if I write a story and, a few months and/or chapters down the road, realize I missed a better name or the name I chose has some undesirable connotations in context or provides an atmosphere-ruining coincidence.
- But I think the real kicker is simply that some part of me is terrified of the awkwardness of giving a character the same name as anybody I know, because then they might read the story and wonder if the character is somehow based on them. And too many of the names that I consider common enough to not lure readers off into looking for hidden meanings are used up that way. This is obviously worst if the character is an antagonist. But it seems just as awkward if the character is a protagonist in accord with everything I’ve written, i.e. a paper-thin character blatantly created for escapist purposes. I am already kind of terrified I might ever meet anybody with the same name as one of my mentally established characters even though I haven’t actually written anything about him. And there’s a well-established convention of not reusing a first name in a work, so this gets even harder with every work; I’m just as worried, what if somebody thinks this character is related to the other character in that story I wrote in second grade? Oh no!!
  
  It’s like not reusing variable names in a programming language where everything is in the same scope. Positively nightmarish.
  And I actually discovered some evidence this is a thing in my past: I found some stories I wrote in 2004. They are possibly the most extreme exemplification of Write What You Know imaginable: the main character, Michael, goes to school and makes friends. That’s all.
  
  Illustration courtesy Brian₂₀₀₄
  
  I kind of want to share these stories, but fast-forward a few years and you’ll see that a classmate named Michael entered my grade and we stayed in the same grade until we graduated.
  
  Hi, Michael. You’re probably not reading this, but the character I created in 2004 is not in any way based on or inspired by you, especially not this image. And unlike later in this post where I name a character after myself, I’m not being sarcastic, really.
  See, this is awkward.

Throwback Thursday Puzzles!

Thu, 23 Jul 2015 23:39:44 +0800

Wow, there are so many cool things in my old folder. I could probably create and schedule enough filler posts to make my streak last through my week-long trip and back. I guess I won’t, though, because I don’t want to dilute my textwall-draft brand more than necessary and there are a few text posts that I fully intend to post before leaving. Or at least one. Although on second thought, it’s possible they might actually not be as interesting as posts like this one about the adorable me from the past. As Pablo Picasso once said, “Youth has no age.” (Yes, I totally just went on BrainyQuote and searched for “youth”. Forgive me, please.) Oh well.

Today’s throwback theme is old puzzles! Particularly picture ones! In reverse chronological order by last modified time, because I said so! All the image puzzles are puzzlehunty in the sense that you’re supposed to end up with a single word or short phrase as your final answer.

`art/hidd3n/p06pre2.png` (2010/10/31)

A straightforward one to start. I have no idea what’s with the filename, though.

`haxxor/purity2/logic.html` (2010/10/10?)

My file hierarchy is really weird. I don’t think this time stamp is when I wrote the puzzle because it was part of a silly static site setup I created (but never actually put anywhere), and I probably edited and regenerated stuff like the breadcrumbs many times, but it’ll have to do.

This is also funny because the title of the HTML file is “Logic Puzzles” and the description starts, “These puzzles were made when I was really bored…”, but there’s only one puzzle.

Well, it’s better than an under construction page, I guess.

I’ll quote the entirety of the old instructions as I wrote them, even though they’re really verbose, since it’s easy to scroll past them:

numbers.bmp

Wed, 22 Jul 2015 14:06:09 +0800

Mom dug up an old hard drive for me to find photos of my elementary-school self participating in the same math competition I’m presenting at in a week. I discovered a lot of other interesting old stuff there. So today’s filler post image for the streak is courtesy of Brian_2003/03/23. I don’t think it means anything, but sorry, I really really need to work on that presentation.

Translation Party

Tue, 21 Jul 2015 23:53:12 +0800

Just a short anecdote for the streak today. Hmm, I guess this developed beyond being just another filler post, which is good.

In addition to preparing my presentation, the other job I have to do for the math competition I’m attending in a week or so (not as a participant, okay?) is translating various guests’ speeches between English and Chinese.

The speeches’ length and formulaicness really get on my nerves, but then again my standards for speeches were skewed upward by Richard Forster’s speeches during the opening and closing ceremony of IOI 2014, but on the gripping hand I don’t think it’s that hard to at least try not to be formulaic and I really can’t see any effort on their part whatsoever. Off the top of my head, pretty much all the speeches tend to go like this:

Welcome!
Math is great!
This competition is great!
The city hosting this competition is great!
The college hosting this competition is great!
You contestants are great!
Good luck!

Except each bullet point is a paragraph that lasts a minute.

(Ninja edit: Which is not to say they didn’t put any effort into their speeches at all, but that much of the effort seem misguided to me. I don’t see how anybody who has been in the audience for one of these speeches can overlook the same flaws in their own. Unless it’s like, at some point in the natural life cycle of the human brain, people spontaneously start enjoying these safe and repetitive speech topics instead of some earnest and maybe lighthearted advice and anecdotes and jokes? Like how people somehow start enjoying spicy stuff, or the bitter flavor of beer and wine, or writing teenage-angsty ranty posts complaining to nobody in particular like this one? Tough questions.)

Anyway. My mom actually does most of the translation but I am the grammar stickler post-processor and we work together on the hard parts. The second hardest things to translate are idioms. The hardest things to translate are quotes. It turns out that lots of people find translated quotes to Chinese and it can be incredibly difficult to reconstruct their English versions. Here is the quote that today’s story is about, which we were tasked with providing the English translation (or original) for and which the speech attributed to 克莱因 (trad.: 克萊因).

A*

Mon, 20 Jul 2015 23:22:35 +0800

Nope, still no meaningful post today. Instead here is a pretty diagram of the A* search algorithm (A-star in English, for my search crawler overlords). At least, I hope it is; I spent more time fiddling with the pretty colors than making sure the algorithm I implemented was actually A*. It looks right, though? In the background, red component measures traversed distance from start, (inverted) green component measures difference between the traversed distance plus heuristic distance and the theoretically optimal heuristic distance from the start, blue component measures heuristic distance to goal.

Phone II

Sun, 19 Jul 2015 23:59:49 +0800

Here are two screenshots of the Android 3x3 grid lock we dealt with in the phone post. Part of the reason I don’t have a real post today and am instead writing filler for the streak is that I wanted to include this 3x3 lock in the programming presentation I’ve been indirectly complaining about in the last few posts, and I couldn’t find any nicely licensed screenshots to illustrate it, so I made these screenshots myself, and then I spent somewhat more than an hour researching copyright law and listening to a talk about it before posting them.

MIT Course Number Mnemonics

Sat, 18 Jul 2015 23:45:41 +0800

When I first realized it might be helpful to start trying to remember the correspondence between MIT courses and their numbers, I expected a list of mnemonics for this correspondence would be one of those Things That Should Exist On the Internet. I’m pretty surprised it doesn’t. I mean, MIT has, what, at least 100,000 alumni; as far as I know, nearly everybody who goes there speaks the number correspondence fluently, so they have to learn it; and the science of mnemonics has been with us since the ancient Greeks and people who understand its usefulness can’t be uncommon, especially not in such a prestigious institute of higher education.

What gives?

I’m not sure. Maybe it’s just that nobody has posted their mnemonic set on the Internet out of embarrassment? My mnemonics are pretty bad too, but hey, Cunningham’s Law — if you’re reading, feel free to add better ones in the comments, or to criticize my horribly unenlightened and stereotypical characterizations of your courses, to make this thing better. Or maybe it’s out of concern that nobody else will find it useful? I get that feeling but my streak compels me to ignore it now, as it has for the last dozen posts or so. Or maybe they just didn’t optimize for search engine findability, so I can’t find it? I hope this post fixes that.

Actually, I guess the most likely reason is that maybe most people don’t actually have all the course numbers memorized with perfect recall, only the handful of most common ones they and their friends are in, and it’s perfectly fine to ask for clarification when an unknown number comes up in conversation, so nobody ever feels like they need to bother with mnemonics for every single course. Feels sensible to me.

But anyway, I’m not most people.

The most comprehensive resource of courses and numbers, including their history, appears to have once been at http://alumweb.mit.edu/clubs/sandiego/contents_courses.shtml. Many, many links point there. Unfortunately, it is dead and I cannot find its new home, if it has one. Fortunately, there is an archived version on archive.is; on the other hand, I am not sure whether any updates have occurred since it was archived. A more recent version with course populations from 2005 is this chart linked from the MIT Admissions blog post Numbers are names too.

Variance

Thu, 16 Jul 2015 23:59:25 +0800

It’s olympiad season. Taiwan placed 18th in the IMO rankings1. Next day there are news stories about how it’s our “third worst performance in history”, and commenters drawing casual arrows from changes in Taiwan’s standardized tests and curriculum to this result, and the Ministry of Education saying they’d review their procedures or something. What. Did you forget our performance last year? Do you think our olympiad training system is completely overhauled on an annual basis, or has even a tangential relationship with the overall education system?

Phone

Wed, 15 Jul 2015 23:58:02 +0800

tl;dr: anybody want to add me on Line or tell/remind me about other phone chat apps? betaveros as always.

Wow, talk about uninspired post titles.

I got a new phone today. Or, well, it’s second-hand, actually. I try to make electronics last a long time, but I think this was justified given the state of my last phone’s screen:

Besides, I’m going off to college and all. Anyway, the phone is pretty cool. It’s a slick shade of red, it came with a cover and everything, and it has one of those fancy 3x3-grid locks. How secure are those again?

Well, we could just find the answer on StackOverflow, but that’s boring.

Chi Banner

Tue, 14 Jul 2015 21:21:36 +0800

Okay, I think I’m figuring this out. When I make a filler post for the streak, it should be an unabashed filler post, so I can accumulate some of the blogging time I find each day to work on a serious post (and for doing the other important stuff I should be doing!) instead of wasting it right away. Life. I’m programming something for Dad involving a parser using Jison, and one of the tasks involved stuffing a custom lexer into the parser.

US$2,857

Mon, 13 Jul 2015 23:20:09 +0800

= within 15 cents of $20,000/7
= NT$88,661, by Google’s current exchange rate

= 739 hours of Taiwan’s hourly minimum wage or 4.43 months of Taiwan’s monthly minimum wage
= 317 hours of Massachusetts’s minimum wage (7.94 weeks or 1.85 months assuming a 40-hour work week)
= 1.2~1.7 weeks of a list of high tech internship salaries as featured on Slate

= 2,955 plates of Sushi Express
= 1,478 cheap boxed lunches (at NT$60 each), which would last one person 1.35 years at 3 per day
= 1,122 Big Macs, price in Taiwan, or 596 Big Macs, average price in U.S. (January 2015)

Self vs. Other

Sun, 12 Jul 2015 23:59:54 +0800

My mom says I blog too much about myself. I am completely guilty of that and this post is mostly not an exception. Sorry.

It’s not that I wouldn’t like to write posts about others and for others. But I know more about myself so obviously there’s more I can write about myself. It’s kind of a habit, and it’s been a very personally helpful habit. I discover lots of things when I write introspectively. But I’m a very weird person and a lot of the insightful things I discover when doing this are things I doubt I can generalize to other people. I tried getting a lot of my friends to join HabitRPG when I discovered it, but it was nowhere as effective on them as it was on me.

What else could I blog about? What else do people blog about?

World-event-inspired topics?

Sheep

Sat, 11 Jul 2015 22:42:57 +0800

Ok I give up I don’t have any material and don’t feel like preparing any because the influx of IMO problems, including the shortlist, is too fascinating. Instead, here is a joke quoted verbatim from TVTropes (CC-NC-SA). An American anthropologist has been studying a tribe in Africa by living with them for a year. One day, the chief called him into the chief’s hut. The chief sighed. “Well, my friend, it seems that we must ask you to leave.

Nuclear II

Fri, 10 Jul 2015 11:40:47 +0800

(streak)

This is not any better than the first installment, but I need to post. And then, you know, do homework and presentations and stuff.

Dr. Carver had just managed to drill past Dr. Perkins’s cranium when she heard the door behind her creak open.

“Ha! You walked right into my trap!”

She turned around. Dr. Perkins was standing in the doorway.

She looked down. Yes, they were both Dr. Perkins, she’d know that pair of glasses and spiky hair anywhere.

She looked up. Well, the guy in the doorway was wearing a set of black robes outside his white lab coat, but other than that, they really looked completely identical.

“What?”

Time Management

Thu, 09 Jul 2015 23:35:50 +0800

All through high school I had really high standards for myself. Not the grades, mind you (I admit, humblebrag, my grades were always uncomfortably high, probably as an expected but still sad byproduct of this process (yes, I’m actually complaining about grades being too high. I don’t want my report card to have lots of Bs or Cs, but I really didn’t need to pour enough resources into schoolwork that I graduated as valedictorian, when there were so many other personally and socially meaningful things I could be dedicating effort into creating — but that’s a subject for another post (humblebrags all the way down. Somebody get some internet pitchforks and poke some sense into me))), but simply how I managed my time for doing homework.

In my opinion: not very well. I always spent too much time surfing the internet and doing things less urgent than homework, then ended up sleeping at midnight or one o’clock or whenever often to finish what I should have done earlier.

And yet, compared to many of my friends (definitely not all, though), that’s not late at all and the amount of buffer time I had between finishing work and having it due was positively luxurious. But then, I suppose, I didn’t have the same amount of math homework. But to counter my excuse, I had additional responsibilities such as practicing olympiad problems and preparing weekend presentations and translating the school newsletter. So I don’t actually know if my workload was significantly lighter than average or not, ergo I don’t know whether my time management skills were significantly better than average or not. It seriously doesn’t feel like they would be.

And allegedly, even when I’m procrastinating, it’s more productive than my friends’ procrastination, maybe even Paul Graham’s good type of procrastination. Often when I gripe about how much my former self procrastinated they will ask me what I’ve been doing and, after hearing the answer, tell me this. What have I done to put off homework? Oh, I did some olympiad math problems, committed to my GitHub projects, read a bunch of programming blogs, organized my old chemistry notes from two years ago, and surfed the Stanford Encyclopedia of Philosophy. Yeah. Total waste of time. Meanwhile certain friends surf 9GAG whenever they get the chance. (Which is not to say that I don’t procrastinate in obviously unproductive ways sometimes — I surf reddit, YouTube, and TVTropes of course. Sometimes I even just read my own blog or dig through old folders in my computer. I’m weird. But anyway.)

Bilingualism II

Wed, 08 Jul 2015 23:16:46 +0800

我本來還想把這一篇用英文跟中文各打一次來實際比較看看，但這已經被困在草稿匣夠久了。一直做重複、吹毛求疵、沒有效率的修改本來就是我寫心情文時的弊病，如果再要求修改時要保持兩種語言版本的同步的話，大概寫到天荒地老都寫不完。（如果讀者沒有讀過我最近亂發的文章，故事都是這樣的：我覺得我在草稿匣累積了太多寫一半的文章，所以在畢業後，我在六月十一號決定從那天開始每天發文，直到我出國，目的是強迫自己把那些草稿寫完，中間還亂發很多其他我本來大概不會寫下來的東西。其實還滿有成就感的。另外，如果你的中文沒有很爛的話，如果你在任何地方認為我寫的中文不流暢或是可以寫得更好，請毫不留情的留言批評。這也是一件我發現我在寫中文方面很缺乏的經驗，我會很感謝。當然，根據以往經驗，懇求讀者留言沒什麼機會成功。）

If you came to this blog or this post hoping to read English, sorry not sorry. It’s only fair, really, given how many people on Facebook can’t read the massive English textwall posts I’ve spammed them with for so long.

常常有人訝異我的英文這麼好。有時候這些人還會問我怎麼學的－－碰到這種問題我都不知道要怎麼回答。喔，很簡單啊，只要選擇在一個主要說英文的國家出生，然後跟一群從國外回來的同學一起讀有80%的課是用英文上的學校連續讀十二年就好了。

偶爾也有人知道我是雙語部的或在不同的情況下認識我，反而會覺得我的中文比他們預期的好，例如我的駕訓班教練。其實我在雙語部還是上了十二年的國文課，進度理論上跟其他學校一樣（「理論上」三個字要強調），我也跟身旁很多親戚朋友用中文溝通了更久。比奧林匹亞競賽的經驗應該也讓我認識的上普通國語教學學校的學生，比其他雙語部同學認識的多。所以這應該也不奇怪吧。

但是。其實我對這兩個語言的精熟度其實還是差很多。日常對話沒問題，不過我對英文細枝末節的部分瞭解的比中文多太多太多了。家裡有不止一本「常見英語錯誤」類的書，我小時候會當小說讀－－我是一個很奇怪的人。在學校課程中，我編輯自己或他人的英文文章是一天到晚的事情，什麼奇怪的句子跟構造都碰過、想過、修理過。還有些時候，我會很自然的寫出一個英文單字，然後發現我不知道為什麼自己會知道這個單字的意思，但就是有一種感覺告訴我，對，subsist的意思就是「存活於只有最基本的需求被滿足的情況」。跟中文比較：有時候，直覺也會告訴我有某一個成語是可以用的，但我只能清楚想到這個成語的兩、三個字。聽起來很「對」，不過我就是想不到第四個字是什麼，或是怕前三個字換成錯別字，再加上懷疑整個成語意思根本不是我模糊腦袋裡現在浮現的，因為我認得這些字字面上的意思，但無法說服自己為什麼它們合在一起可以解釋成這種意思，最後只好放棄，用國小白話文的措詞就好了。

「總覺得，我在用任何偏離國小程度的白話文的詞彙的時候都是假裝的。」

我在舊一點的草稿寫出了這個句子，不過那一串「的」字讓我覺得怪怪的，現在想想，沒有人跟我討論過寫出這種或其他奇怪的句子時應該怎麼辦。哪一些「的」可以省略？有辦法把句子重寫（recast）避開嗎？還是不管它，我覺得它聽起來很奇怪純粹是錯覺，多讀一點中文就會發現根本沒什麼大不了的？

使用兩種語言的方法也差很多。看看這個部落格就知道了。我相信我在學校雙語部外的大部分台灣朋友不會試著去理解我關於自己長篇大論的英文作文，但長篇大論的文章還是我最認真表達自己的地方。反觀我的中文短文，都通常是那種搞笑、釣讚、裝弱的文。（不，我真的很弱。）我不時會發現自己在網上逛到一個陌生人的心情文，看得津津有味。我們之間的關係頂多是朋友的朋友的朋友，我只知道我跟他應該都喜歡數學這個共同點罷了，但因為語言，我在那些瞬間覺得自己瞭解他勝於瞭解幾乎所有在我身邊講中文的朋友。我自己怎麼看這件事都覺得不合理，有點慚愧。

我回去讀了我第一次寫的關於雙語的文章，可能有一點過火：後來證實，在我的朋友中似乎真的有會純粹為了抒發感情而寫七言律詩的人。而且，我講中文的朋友圈裡，文學類佔的比例本來就應該比他們在整個社會裡佔的比例少很多。在學校跟在生活裡，吸收英文多於中文（而且數學多於英文）是我做的選擇，只是我自己不知道選擇的中介點好不好罷了。是否，我花在跟講中文的親戚朋友互動的力氣不夠？

A List

Tue, 07 Jul 2015 20:56:53 +0800

(streak) ≥1 of you should know what is being referred to. Oh yeah, I love being first. Of course the approximate price is that I have to expose the world to the innocent naïveté of my fourth-grade self. So far nobody mean has ventured there yet, but who knows. Darn, two years. Darn, Cards Against Humanity. I need more of that in my life. I don’t know what else is happening but music is good.

Drop-In Filler

Mon, 06 Jul 2015 21:50:05 +0800

(streak)

I’ll probably be making filler posts for a while until I make decent progress on linear algebra and programming work, including another presentation.

Let’s listen to some more music.

(8,9,7)

Sun, 05 Jul 2015 10:09:29 +0800

(streak)

I always tell myself, okay, I will actually just draw something facetiously and get it over with, nobody comes to this blog to admire my GIMP mouse doodles, but then perfectionist tendencies kick in and I get carried away and it ends up taking more than an hour or so.

More Fiction (Part 2)

Sat, 04 Jul 2015 23:47:49 +0800

Part 1 was here. This is still part of the daily posting streak I have openly committed to and standard disclaimers still apply. Just as in my original post, back to the flip side — let’s see what I have to do to write fiction to my own satisfaction. And this time I have a guide: the list I made in the first part of this post. Could I create fiction I would enjoy reading?

1: I enjoy calling things before they happen…
2: …I also enjoy the Reveal for questions when the author has done something clever I didn’t catch…

Well, obviously, I can’t predict things in my own plot. But I can develop riddles in the plot, set up expectations and drop subtle clues and use Chekhov’s Tropes. Can I?

Cognitive Asymptotics

Fri, 03 Jul 2015 23:08:25 +0800

Short blog content for daily posting streak. Standard disclaimers apply. Not much to see here. At some point in the past, because I was a bored teenager, I memorized this. So now, in theory, I can tell you the capital of each state of the U.S. This is already a lame trick, but as I realized yesterday, it’s made even lamer by the fact that the data structure I chose only supports O(n) lookup.

More Fiction (Part 1)

Thu, 02 Jul 2015 13:41:12 +0800

I’m going to do it again! I’m going to break a post into parts to milk it for the daily posting streak. Desperate times call for desperate measures.

This is mostly a self-analysis post though.

WARNING: This post contains many, many TVTropes links. If you are like me and need to be productive but are liable to being sucked into TVTropes, maybe you should find a way to commit to not clicking on any of these links, or just stop reading. The obligatory xkcd is kind of long and also featured on one of the TVTropes links I’ve already made, so I’m not going to embed it.

I blogged about this before in 2013 — how I felt that the analysis trained into me by English class was dulling my ability to appreciate and write the types of fiction I really enjoyed. After thinking about it I realized the mismatch goes deeper than that. Because the things I seek the most in fiction are escapism and entertainment. I like simple fiction with obvious (though maybe not that obvious) Aesops and extreme economy of characters via making all the reveals being of the form “X and Y are the same person” (which does not quite seem to be a trope but may be an occurrence of Connected All Along, with the most famous subtrope being Luke, I Am Your Father (which is a misquote!), and is also one common Stock Epileptic Tree, so maybe this isn’t the best example), because not only are such reveals fun, they make the plot simpler. What can I say, it works.

The qualities of being thought-provoking or heartwarming are only bonuses for me; needless complexity in the number of characters or plots is a strict negative. Sorry, I don’t want to spend effort trying to remember which person is which and how a hundred different storylines relate to each other if they don’t build to a convincing, cohesive, and awesome Reveal, and often not even then. And I like closure, so I feel pretty miserable when writers resolve a long-awaited plot point just to add a bunch more. Because of this I am ambivalent about long book series; most of my favorite works of fiction have come in long series but starting a new one always gives me Commitment Anxiety. Even when there’s closure, when I finish an immersive movie or book I’m always left kind of disoriented, like I’ve just been lifted out of a deep pool and have to readjust to breathing and seeing the world from the perspective of a normal person on land. I like when I’m reading good fiction, but I don’t like going through withdrawal symptoms. If I want to read complicated open-ended events, I’ll go read a history textbook, because at least the trivia might come up useful some day; if I want tough problems I’ll just look at real life and think about the possibility of college debt and having to find a job and everything. (If it wasn’t obvious yet, this is why I hyperbolically hate on Game of Thrones often.) Even worse than all of this is multiple paragraphs full of scenery and nothing else, unless of course parts or maybe all of the scenery are Chekhov’s Guns.

Some part of me is embarrassed to admit this because I’ve been educated for so long about deep literature that makes social commentary or reveals an inner evil of humanity or whatever. But then again, I don’t really need an education to appreciate the simple, fun fiction I apparently do.

So: there are a lot of famous classics or mainstream works I can’t really enjoy too much, or in some cases, at all. And yet, sometimes a random story or webcomic will appear and I just won’t be able to stop reading. Why? I decided to try making a list of things I like in fiction:

DOUBLE POST

Wed, 01 Jul 2015 01:05:52 +0800

20 posts so far in my daily streak, ignoring the time I posted after midnight but including exactly one of this post and the commitment-starting post. You pick which one. The arithmetic works out either way. My last four posts have been made with less than two minutes to spare before midnight, and my last post in particular made it by just seven seconds. This is working as intended in that I’ve knocked out nine drafts that I’m pretty sure would have rotted in my draft folder for at least a few more months otherwise, and I’ve also jotted down more spontaneous thoughts and posted them instead of postponing them until they was too late to be applicable. But this is also a problem because I can’t spend every day procrastinating blogging and then frantically blogging before midnight — I have some serious programming work to do, and a talk to prepare for, and, of course, linear algebra homework!!!

I’m kind of stuck here so

Quixotic Reimagining of Standardized Tests (Part 2)

Tue, 30 Jun 2015 23:59:53 +0800

If you remember, Part 1 was here and my goal is to construct a theoretical system of standardized tests that I would be satisfied by. Here’s what I’ve got. As usual, because of the daily posting streak I have openly committed to, standard disclaimers apply.

We’d have a first-tier test like the SAT, except this will be explicitly designed not to distinguish among the high performers.

The goal of the test is to assess basic proficiency in reading, writing, and mathematics. Nothing else. Most good students, those who have a shot at “good colleges” and know it, will be able to ace this test with minimal effort and can spend their time studying for other things or engaging in other pursuits. Students who don’t will still have to study and it will probably be boring, but the hope is that, especially if you’re motivated to get into a good college, there won’t be much of that studying.

For colleges, the intention of this test is to allow them to require this test score from everybody without having to put up disclaimers that go like,

there is really not a difference in our process between someone who scores, say, a 740 on the SAT math, and someone who scores an 800 on the SAT math. So why, as the commentor asks, is there such a difference in the admit rate? Aha! Clearly we DO prefer higher SAT scores!
Well no, we don’t. What we prefer are things which may coincide with higher SAT scores…

zzz

Sun, 28 Jun 2015 23:58:37 +0800

(daily posting streak)

Facetious paintbrush dragon filler is best filler!

Coming Up with Blog Post Titles Is Hard

Sat, 27 Jun 2015 23:59:03 +0800

(Disjointed blog content, posted as part of a daily posting streak I have openly committed to; standard disclaimers apply)

Blogging is weird. I’m still nervous when I post stuff because I’m concerned I’m wrong, and end up looking unprofessional or attracting a bunch of Cueballs or something.

Before I told people about this blog, during the time when 100% of its traffic came from its coincidental placement in search results, I didn’t have to worry about this. Now, I choose my words. Because some Important Person™ might show up. Maybe even misinterpret something I said and/or get furiously offended at a badly phrased joke.

I also fear that I’ll update my beliefs quickly; maybe I’ll change my mind or discover a much better argument for the other side really soon. But the blog post would still be there, displaying my old belief, giving the reader an inaccurate or misleading impression of myself. People might even chat with me to argue about it, and then I have to admit I’m wrong oh no! It feels a lot better admitting I’m wrong on my own turf, in my own time.

This passage from Lord of the Flies comes to mind (I had hurriedly reread the book as ammunition for the AP Literature test and noticed that my past self had marked it):

Last Step

Fri, 26 Jun 2015 22:37:45 +0800

It is more than slightly intimidating to go into the room through the big sliding door and see everybody dressed up in full-on green surgical garb with masks and hair nets. I don’t remember this part. Feeling a little vulnerable, I change my clothes.

I ask to listen to my iPod during the operation — I remember being able to do this during the operation four long years ago when the subject of today’s surgery was inserted into my shoulder — but the nurse(?) says it’s best not to do that because they’ll be using something electric to stop the blood. Instead I can listen to music played from a computer in the operating room. Well, okay then.

She escorts me through a bunch of twisty little passages to said room. The computer is a dual-screen Windows XP. The nurse shows me that there is a folder with random albums sorted by year. I poke through the folders and create a playlist in Windows Media Player interleaving 1989 with a collection of classics from 五月天(Mayday). Then I get on the operating table and wait. One of the nurses compliments me on my choice of the latter band. A few tracks later, I deduce that my interleaving had been to no avail because the media player was set to shuffle. I spend a lot of time on the operating table at first not doing anything except stare at the ceiling. There is a white three-legged contraption there, with each hinged limb ending in a large blue-rimmed circle of surgical lights. There are white sans-serif letters inscribed on the rims, saying Chromophare® E 668 and Berch-something. I think the “something” was a synonym for “say” or “tell”. An after-the-fact search says it’s Berchtold. Typical human memory.

Later I am covered with lots of green cloth, which blocks out the ceiling. Instead, I can only see a clipboard and random paper forms on the left side of my peripheral vision, presumably propping up the cloth. The clipboard is a highly translucent pink. The form on top is yellow and has a box saying something about somebody paying; the form on bottom is white with a black-and-pink-striped right border. The clipboard’s clip also has random streaks of black marker across a white sticker.

Music plays.

Quixotic Reimagining of Standardized Tests (Part 1)

Thu, 25 Jun 2015 23:19:42 +0800

Life update: I got my driver’s license from the place where I learned to drive. Then I drove home from there with my mom, and it was zarking terrifying.

Also, WordPress says it has protected my blog from 3⁸ spam comments.

Early in the morning tomorrow, I have a small surgical operation, so I can’t sleep too late. (Well, it ended up being pretty late anyway. Darn.) Therefore I think I’m going to do something unprecedented on this blog for the daily posting streak: I’m going to post an incomplete non-expository post.

Yes, the only purpose of the title is to get initials that are four consecutive letters of the alphabet..

One of the more argumentative post sequences on my blog involved ranting against standardized tests.

My very first stab was probably the silly satire directed at the test everybody has to take that takes up two hours per day of an entire week. Once college became a thing in my life, I wrote a humblebrag rant after I took the SAT and then a summary post after I snagged this subject for an English class research paper and finished said paper.

It should be plenty clear that I am not ranting against this part of the system because it’s disadvantageous to me.

But it should also be said that I’ve read some convincing arguments for using standardized tests more in college admissions (Pinker, then Aaronson). Despite the imperfections of tests, they argue, the alternatives are likely to be less fair and more easily gamed. The fear that selecting only high test-scorers will yield a class of one-dimensional boring thinkers is unfounded. And the idea that standardized tests “reduce a human being to a number” may be uncomfortable for some, but it makes no sense to prioritize avoiding a vague feeling of discomfort over trusting reliable social science studies. Neither article, you will note, advocates selecting all of one’s college admits based on highest score. Just a certain unspecified proportion, one that’s probably a lot larger than it is today.

And although I wish the first article linked its studies, I mostly agree with their arguments. So this puts me in a tricky position. These positions I’ve expressed seem hard to reconcile! So, after arguing about all this with a friend who told me things like

I think you fail to understand how anti-intellectual american society is

(comments on this statement are also welcome) I think some clarifications and updates on how I feel are in order.

2^10 Words

Tue, 23 Jun 2015 15:31:12 +0800

Vacuous content for posting streak. Disclaimers apply, particularly “entirely unlike anything previously on this blog”.

Like I said, studying. Furiously.

Scary Cars

Mon, 22 Jun 2015 22:27:14 +0800

(Part of a daily posting streak but for once I don’t think I need to apply the disclaimers to this. If you thought for even one second that the title was a palindrome, I’ve succeeded. It’s not. I don’t have a good title. Okay, maybe slap the disclaimers onto that part.)

The first time I drove a car was on 5/18. I think. I might be off by a day or so. Most of that day’s lesson was spent learning to go forward and backward, accelerate and decelerate smoothly, and turn the wheel without getting my hands tangled up. My coach made me count out loud how many circles I was turning: 一圈半圈半圈一圈etc. It felt kind of stupid when I was doing it, but I guess in the end it helped, and eventually once I got the hang of turning the wheel, I just subvocalized it and my coach also tacitly stopped bothering me about it.

The first time I activated a turn signal light was probably on 5/26. That was the day I wrote in my TIL log that, when you turn the steering wheel back from the direction you were turning, the turn signal lights turn off automatically. After you think about it, this is a pretty sensible thing for turn signal lights to do, but when I first learned this my mind was utterly blown. Wow!

It’s like when you’re turning and you turn on the turn signal and it starts clicking this steady beat to increase the dramatic tension, like you’re doing a trick in a sports driving game and you have to quickly hit the right sequence of buttons on the controller. Then you actually turn the corner and then turn the wheel back, and as the wheel makes its smooth sliding sound back to its upright position, the beat stops like a resounding V7 to I resolution, as if to congratulate you on executing a beautiful turn without crashing into another car or driving off the side of the road.

That’s what it feels like, anyway.

On slow days, when you’re halfway through a turn but the drivers ahead of you are waiting in a queue that stretches on forever on the practice track, you can shift to the parking gear and use the turn signal’s beat as a metronome and sing along to it too. I do.

Or, of course, there’s the obligatory xkcd:

index.txt

Sun, 21 Jun 2015 20:52:45 +0800

That’s the name of the text file that comes up in MacVim when I hit option-shift-Z. I use it for quick notes and editing stuff to later be pasted into webpage forms, especially complicated JavaScripty ones (e.g. Facebook, Twitter) that don’t play nice with Pentadactyl’s popout editor functionality. The keyboard shortcut is set in Quicksilver, although I was doing something similar even on Windows with AutoHotKey.

Over time I tend to hoard stuff here. Vim says it has more than 40,000 words and 300,000 characters. It contains seeds that never grow into blog posts, planned tweets I later abandon out of embarrassment, preemptively composed comments that never get posted, carefully written text I’m paranoid might get deleted by the Internet, and more. For today’s frivolous post (part of a daily post streak, standard disclaimers apply, etc.), here are some excerpted context-free highlights, like a personal extended game of “What’s in your Ctrl+V right now?”. The task of interpretation and/or guessing the context is left up to the reader. Have fun! See you tomorrow!

My DNSE Story

Sat, 20 Jun 2015 17:12:13 +0800

(Something something something daily posting streak something something standard disclaimers. My schedule is tighter than usual because IPSC is tonight and runs right up until midnight. Anyway, here’s my logic with posting this: given how long I’ve committed to posting, I’m probably going to have to dig deeply enough into my reserves to include it, and to be authentic I can’t edit the story more anyway, so I might as well do it now. (Also maybe this will pressure me into finishing and posting one of the real short stories in my blog draft folder, the same way I feel pressured to make a good puzzle after posting a bad one.) I’m not even going to reread my story because I don’t like cringing at my own writing without being able to edit it, but hopefully that makes it bad enough to be entertaining. If you didn’t know, this was for an MIT preorientation program application. Tell me if it’s bad to repost application stuff. I hope not.)

(Oops this introduction is about as long as the actual story now.)

Tell us a short story in the available space below. Your inspiration is only one word: nuclear. Go!

8 Songs for 18 Years

Fri, 19 Jun 2015 13:40:30 +0800

At some point I thought, hmm, maybe this blog would benefit from some more sentimental, memory-capturing music/videos, like I chose for my end of 2013 post or my end of 2014 post. (Yeah, I link to my own posts alarmingly often. I think that’s kind of weird. I don’t know.)

Obviously, because you’re reading this already, I decided to follow through with that idea. There’s no particular significance for posting this now — it’s not my birthday or anything, as the title might suggest; it just has a nice ring to it — except of course that I’m starting to get mildly desperate for content for my daily posting streak exercise. Standard disclaimers apply.

This is mostly for my future self. I should note that, although I like these songs, this is not a list of my absolute most favorite songs ever. You can tell because there isn’t any Coldplay or fun. (the band.) Instead, each of these songs was chosen to be meaningful to myself and my life in at least two different ways that generally don’t overlap with the other songs. This was difficult but I think I managed it — you know, how constraint breeds creativity and everything? Also, they’re arranged by approximate chronological order of impact. But it also means that this list isn’t going to be that meaningful to anybody other than myself.

Also, I have a long list of class-of-2015 sentimental songs, which I’m not including here because I think there are so many that they deserve a separate post. Will I avoid procrastinating and feeling awkward for long enough to make such a post? Stay tuned!

shrugs Whatever, enjoy the music or stop reading now if you want.

1: Simon & Garfunkel - Scarborough Fair/Canticle

Two Points on Photography

Thu, 18 Jun 2015 23:55:52 +0800

(Uncohesive blog content, posted as part of a daily posting streak I have openly committed to; standard disclaimers apply. Whew, made it by a few minutes…)

This essay was partly inspired by but mostly orthogonal in purpose to dzaefn’s essay on a similar subject, Humans, Photographs, and Names. I agree with many of its points, although I deviate in that I think it’s more important for my Facebook picture to identify me than to inform about me (there’s the rest of Facebook, plus my maybe half a dozen other sites, for doing so). Part of the problem for me there, and part of the reason I hang on to my nine-letter random handle from fourth grade, is that my names, first and last, are so commonplace. Among the people who share them (according to DuckDuckGo) are a New York Times tech writer, more than one computer science professor, a photographer, a couple doctors, and some guy who did some sort of graphics work for a short clip and two movies. This means that, to somebody not already in my social circles trying to match me to my account, my Facebook photo is my primary tool for disambiguating myself from all these other people, and I don’t think there is anything that could do that job quite as precisely as a picture of my actual face and body.

Still, I agree enough to be bothered by having a profile picture suffering from “the whole extent of photographic informational void”. I always planned to add some GIMP layers to the photo to indicate context and content more precisely. Except I procrastinated and it got more and more awkward to do this as time went by, since as far as I know, normal people update their profile pictures only to reflect more recent events, especially when they’re important. Like, you know, graduating from high school? So yes, I’ve been waiting to do this for an entire year now.

Eh, to hell with awkwardness. That’s the spirit of this daily-posting exercise.

(Fun fact: The code in what I’m about to set as my profile picture, if I don’t procrastinate even more, is real IOI 2014 code I submitted successfully (for rail, as previously featured; the visually selected fragment was the key fix for the final bug I fixed). Except I actually had to manually retype my code printout to get the picture because I lacked the foresight (sound familiar?) to save an electronic copy of my IOI submissions.)

Also, I’m glad this isn’t a smiling photo because I feel like it’s easier to appreciate happy posts from a person whom one associates with a serious face, than serious posts from a person whom one associates with a happy face, and I want both types of posts to impact people when I post them. I could be overgeneralizing from my own feelings though. If you are reading this and want to chat me feedback (as way more than one of you has been doing), I’d welcome more data points on this issue.

That’s not what I really wanted to rant about in this post, though.

Why do people take photographs?

Signal Boost

Wed, 17 Jun 2015 21:59:18 +0800

(Short blog content, posted as part of a daily posting streak I have openly committed to; standard disclaimers apply)

For the interested, I wrote a post summarizing issues in copyright and patent law on a new blog for a school club. Actually, if you’re reading this post, you’re probably already interested enough / bored enough to read that post, so go read it. I think the videos are worth watching despite their length, but I tried to summarize the key points in text, so decide how much to read or watch depending on how much spare time you have.

I don’t know if that blog will work out, but anyway WordPress tells me I have 8500% more followers on this blog than the other one, even though I have doubts about how many of those followers actually read anything I post at all, so I thought I should link to that post here. Also, by publicizing the blog, I get to shame my friends and fellow club members into posting so that it doesn’t look so empty. Social media expertise, you know?

Spontaneous Thoughts on Teaching

Tue, 16 Jun 2015 23:04:09 +0800

(Disorganized and probably incomplete blog content, posted as part of a daily posting streak I have openly committed to; standard disclaimers apply)

Okay, I’m actually going to try starting this blog post and posting it in the same day.

Story: As a sort of extracurricular activity slash side job, I taught a math class after school once a week to six fifth-graders. It was nominally geared towards some Australian Math Competitions, which my math teacher administers in Taiwan, although in the end I don’t think I achieved this end very well.

After writing this brain dump I realized this was a pretty terrible hackjob; I had absolutely no idea how to teach fifth-graders or how to organize an after-school class, and I still mostly don’t. Parents did most of the organizing, really. And provided refreshments.

And I get paid for this????

Bulleted list of other thoughts:

Wow, I didn’t realize / remember how serious the gender gap between elementary-school students is. I don’t mean the difference between their performance (that might have been the case, but I don’t think I felt a significant enough difference to conclude anything); I mean how fifth-grade boys and fifth-grade girls don’t like to mingle.

When given the opportunity, they would pick team names like, “[members of my gender] Rule, [members of other gender] Drool!” They wouldn’t discuss with each other either. If prompted, they would sometimes point out mistakes in each others’ work, though.

I think this is a phase that people grow out of, and I probably did it myself when I was young. I don’t remember when it ends, but in any case, ugh, it’s so unproductive that boys and girls separate themselves for any length of time at all.

Sigh.

rekt

Tue, 16 Jun 2015 00:36:06 +0800

Darn, I only lasted four days. That’s pretty bad.

And I broke like 90% of my HabitRPG streaks too. I was busy running Monte-Carlo calculations to estimate the number of domino logic puzzles, and forgot about midnight. Okay, before that I spent twice as much time on Flight Rising for whatever reason. Bad life decisions.

I guess that means today I have to post one now, before going to sleep, and one later. Eh, time to harvest really weird mini-posts from nowhere.

Mortality

Sun, 14 Jun 2015 21:00:51 +0800

(Faux-philosophical blog content, posted as part of a daily posting streak I have openly committed to; standard disclaimers apply)

This is a hard essay to write because (1) it’s very irrational and I should (and I do) know better — death by car accident is much more likely than death by an airplane crash, but the latter is scarier because it’s more vivid and we have less control over it, and (2) people don’t like talking about it. When I tried writing it, though, I realized I already burned through most of the down-to-earth worries in the posts I made between April and August of 2010. They still coherently and accurately sum up my current thoughts surprisingly well. And most of the irrational, overly philosophical fears appeared in Thoughts at Midnight. So there used to be a lot of fluff here like this, which was inducing procrastination because I don’t know what to include and what to cut, but now that I have a daily deadline, I cut most of it. Here’s what’s left.

One, xkcd:

Two, bonus quote: As really-long-term readers know, I have had a reason to think that I might actually die in the past few years, a real reason that has stayed with me and gotten me thinking now and then about what my meaning of life is, instead of a short-lived fuzzy philosophical feeling obtained from reading Tuesdays with Morrie (which is not to say that Tuesdays with Morrie isn’t a good book; I just suspect no book can convey everything a personal experience can.) Anyway, it’s over in all likelihood, but the point is that in the middle, I wrote an essay for class in ninth grade, which I find equally coherent and equally representative of my views. The conclusion runs thus:

College Emails

Sat, 13 Jun 2015 09:08:33 +0800

(Frivolous blog content, posted as part of a daily posting streak I have openly committed to; standard disclaimers apply)

Out of boredom and curiosity, I graphed how many emails colleges sent me, excluding the colleges I actually applied to. I am being extremely polite and just calling them emails. I’ve wanted to make this for a long time, but it wasn’t until I saw this post about an email experiment on waxy.org/links that I understood which tools I could use to quantify my emails. (And then I actually made it and procrastinated posting it here for two months. If you look at my GitHub page or activity you might have seen it already, though. Oops.)

I don’t think the results were expected. Other than saying that, I leave the interpretation up to the reader because I’m on a tight blogging schedule. Cool? Cool.

Step-by-step instructions:

Ninety-nine (card game)

Fri, 12 Jun 2015 08:00:00 +0800

(Frivolous blog content, posted as part of a daily posting streak I have openly committed to; standard disclaimers apply)

It is quite interesting that Wikipedia’s article on Ninety-nine (addition card game), plus many of the following search results (ignoring the identically-named trick-taking game that is guaranteed to show up), have the same basic idea but wildly differing assignment of special cards from the one I’m familiar with, which everybody I can recall having played with agrees on. (Admittedly I’ve only ever played this among Taiwanese friends.) The only special-card assignment method that came close was a certain person’s “stuff from my old blog” dumping post I bumped into very accidentally. (His 5 is our 4; our 5 skips to an arbitrary player. The post also clarifies that negative totals bounce back to zero, and includes a clause whereby players must state the running total after playing and lose if they’re wrong. Interesting.)

Anyway, yes, I am documenting the rules to a card game on this blog. I think this deserves to exist online.

These rules are not completely rigorous because I don’t know them completely rigorously. You can use common sense to reach a consensus in corner cases.

Use a normal deck of playing cards, or two or more identical decks if you want. Deal five cards to each player and set the rest aside to form a draw pile. Cards are played into a discard pile in the center. Players sit in an approximate circle and take turns along the circle, playing one card and then, usually, drawing one replacement card from the draw pile, so in normal 99, hands stay at five cards. When the draw pile runs out, shuffle the discard pile to become the new draw pile.

A Commitment

Thu, 11 Jun 2015 08:43:25 +0800

Obligatory life update: I have graduated [from] high school.

But that’s not what this post is about. I contemplated setting up a schedule for my blogging three long years ago, and decided against it, because I didn’t think writing was a high enough priority for me. Well, I am setting up a schedule now: I am going to post something on this blog every day until I have to leave the country (which is happening once before college, so it’s not for as long as you think; but I might decide to continue the schedule anyway after I get back. We’ll see when the time comes.)

Adventures in Unicode Forensics

Sun, 17 May 2015 23:24:11 +0800

What do you do when you get a bunch of files like this from a zipfile? I’ve blurred the messed-up file names because I’m not convinced it’s impossible to reconstruct the Chinese names of people from them and I’d rather err towards being paranoid about privacy. Except for the one file name whose author’s identity I’m OK with disclosing. Back story: I have been tasked with collecting everybody’s Chinese assignments for this semester.

Sylow

Sat, 16 May 2015 00:00:00 +0800

original sillier post

Note on notation: I’m going to use $\text{Stab}(x)$ instead of $G_x$ for the stabilizer subgroup and $\text{Cl}(x)$ instead of $^Gx$ for the conjugacy classes. For the orbit of $x$ I’ll stick with the norm and use $Gx$, although it’s only used in confusing summation notation that I’ll explain with words too.

We keep using this silly counting argument which I thought was something like Burnside’s lemma but actually is a lot simpler, just partitioning the set into orbits and slapping the orbit-stabilizer theorem on.

If $G$ is the group and $S$ is the set then

|Wedge|

Wed, 13 May 2015 00:00:00 +0800

original sillier post

Note on notation: to be maximally clear, I have bolded all my vectors and put tiny arrows on them. Normal letters are usually reals, uppercase letters are usually bigger matrices. Also, $\cdot^T$ denotes the transpose of a matrix.

Let $\vec{\textbf{v}}_1, \ldots, \vec{\textbf{v}}_m$ be elements of $\mathbb{R}^n$ where $m \leq n$, i.e. column vectors with $n$ real elements. Let $V = [\vec{\textbf{v}}_1, \ldots, \vec{\textbf{v}}_m]$. This means pasting the column vectors together to make an $n \times m$ matrix ($n$ rows $m$ columns).

Consider the thing $\vec{\textbf{v}}_1 \wedge \vec{\textbf{v}}_2 \wedge \cdots \wedge \vec{\textbf{v}}_m$, which can be visualized as the hyperparallelogram $\left\{\sum_{i=1}^{m} t_i\vec{\textbf{v}}_i \,\middle\vert\, t_i \in [0,1], i = 1, 2, \ldots, m \right\}$ but is apparently a different thing in a different vector space of things. We wonder how to compute the hyperarea of this hyperparallelogram.

Three Standard Deviations

Thu, 30 Apr 2015 19:30:42 +0800

A PSYCHOLOGICAL TIP

Whenever you’re called on to make up your mind,
and you’re hampered by not having any,
the best way to solve the dilemma, you’ll find,
is simply by spinning a penny.
No — not so that chance shall decide the affair
while you’re passively standing there moping;
but the moment the penny is up in the air,
you suddenly know what you’re hoping.
— Piet Hein

(By the way, apparently spinning a penny is a terrible randomization process; studies have shown they come up tails 80% of the time. Tossing or flipping is better but there’s still a faintly biased 51% chance it lands with the same face it started with (PDF link). Entirely irrelevantly, is the meter amphibrachic? Nice. I’m sorry, but the impenetrable English names they give to metrical feet just sound so cool.)

As May 1 has been coming up, I’ve been half-seriously giving this advice to others who still haven’t decided. But I knew this wouldn’t work for me. I knew where I intuitively wanted to go all along.

The reasons holding me back were more… reasonable. Mostly the money. Call it an id-superego conflict.

I don’t know if the difference between my choices would mean I’d have to take out loans, or work a lot during college, or both. I don’t think either of those things would be difficult. I think tech internships over the summer could just cover the parts assigned to parental contribution (which I’m not going to let my parents pay, unless they start earning a lot more money than expected) and I think I have the skills to get those internships. But of course that’s a tradeoff. Maybe there will be something more self-actualizing or more helpful to my future career that I could do during the summer. I’m not so sure that I’ll find the same drive to program for a job instead of for a personal project I really want to use myself, or for putting off something more boring. I don’t know yet.

(Get it? Drive? Program? Um, never mind, I guess that’s a hardware problem.)

Puzzle 47 / Fillomino [LITS + Walls]

Mon, 30 Mar 2015 20:01:26 +0800

CLICKBAIT PERSONALITY TEST THAT YOU CAN DO WITHOUT SOLVING THE PUZZLE: What do you see in the puzzle image below? I have my own thoughts but I won’t bias you by posting them yet. Sound out your thoughts in the comments below! (I don’t expect this to work but I’d love to be proven wrong)

Okay so apparently how puzzles work is I go nearly a year without posting one and then when I post a terrible one, I feel guilty and obligated to post a legitimate one soon after. Testsolved by chaotic_iak.

This is a Fillomino (write a number in every empty cell so that every group of cells with the same number that is connected through its edges has that number of cells) where each tetromino has had their 4s replaced by one of L, I, T, or S describing their shape, and they obey the rules of LITS — they can touch if they are not congruent, they must all be connected, and their squares cannot form a 2×2 block. In addition, cells separated by a thick border may not contain the same number or letter.

Puzzle 46 / Fillomino [LITS + Extra Region + Walls + Anti-Walls + Inequality + Tapa + Masyu]

Sun, 29 Mar 2015 13:01:08 +0800

5:27 PM phenomist: do you use gridderface to make pretty puzzles?
…
5:52 PM phenomist: actually nvm excel is probably easier lol

Okay I’m sorry this is a horrible puzzle where the rules don’t make sense and I didn’t even get it testsolved. I just wanted an image to concisely demonstrate the capabilities of gridderface, my puzzle marking and creation program, for the project homepage, after somebody expressed interest in using the program to write a puzzle. Then I got tremendously carried away.

Thoughts at Midnight

Sat, 07 Feb 2015 00:49:18 +0800

These are the thoughts that sometimes keep me awake at night.

These are things I don’t want to think about. These are things I’ve spent hours thinking about, never productively. They are worrying, but unlike typical worries in my life, it is fundamentally impractical to take steps to resolve or mitigate them, after which I may rest assured that I’ve done my best. The reason is that they also happen to be either untestable/unfalsifiable or only testable if one incurs absurd and irreversible costs, mainly dying.

Sometimes I explain them away to myself successfully and move on. Sometimes I read what I’ve written and think about these thoughts and do the cognitive equivalent of looking at them funny, as I’m expecting most readers to feel if they get that far — why would anybody be bothered, or afraid, or soul-crushingly panicked about these things? Life is so busy, there are literally more than sixty-four items on my HabitRPG to-do list, and besides, there are so many serious global issues humanity is actually facing right now, and people who are actually deprived of basic rights and resources and have to struggle to stay alive. How can I possibly be bothered by these absurd remote thoughts?

But I know that other times I do feel those emotions exactly. And if I stare just right, I can feel those emotions bubbling beneath the surface in me. Sometimes I can’t explain the issues away to myself, and a deep soul-sucking pang grows in my stomach. I’m irrational — I’m afraid of some of these thoughts — and I have submitted to the fact that there are some edges of my irrationality that would not be worth the effort to fix if just not thinking about them is better.

Sometimes these thoughts make me wish I were not so rational. Sometimes they even make me wish I were religious; it would be easier if (I believed) consciousness were, somehow, special. I suspect if I tried really hard, I could make myself believe something like that sincerely. But I think that’s a betrayal of myself I’m not willing to take. I think there are better ways to remain happy.

I want to maximize happiness. Thinking about more general moral principles will help with that, but the remoteness of these particular thoughts is such that I doubt I’ll ever have to make a choice that would benefit from me having thought about them. At least, I think the chance is small enough to not be worth the negative utility spent thinking about them.

So: “There is nothing to fear but fear itself.”

But I feel frustrated: not thinking about something just doesn’t seem like a solution. I don’t know how to come to terms with just how irrational happiness fundamentally is. And I still can’t resist thinking about them sometimes…

2015 MIT Mystery Hunt

Tue, 27 Jan 2015 11:45:50 +0800

Well, it’s been over a week, which is a long time for blog posts to be delayed after the event they’re documenting in probably all of the world except my blog. So.

I guess this post should start with a bit of background. I’ve been puzzlehunting for… wow, three and a half years now. I was introduced to puzzlehunts from AoPS, when some fellow members got together a team for CiSRA 2011, and I think I’ve participated to some degree in every known internet Australian puzzlehunt since.

But as for my experience with the MIT Mystery Hunt in particular, I sort of hunted with a decidedly uncompetitive AoPS team in 2012 (I think we solved one puzzle exactly), but my serious hunting career began when dzaefn recruited me into the Random team (then Random Thymes) for the 2013 hunt (and I did blog obliquely about it). We didn’t win (and I actually didn’t participate that much because I was traveling with family) but the next year (as One Fish Two Fish Random Fish Blue Fish (1f-2f-17f-255f (I am evidently in a parentheses mood today because as you’ve probably noticed, the amount and depth of parentheses in this sentence are positively alarming (lol)))) we won.

And I do have a half-written post about that which will never get posted (and I also didn’t participate that much, because my family was moving that weekend) but okay, let’s just drop any semblance of chronological coherence on this blog and dump a short version of the list of puzzles and parts towards which I contributed solving, as I wrote them down one year ago:

Moon Shoes

Thu, 15 Jan 2015 18:03:50 +0800

Okay. So. These things: These things are a thing. They’re like mini-trampolines that you are supposed to strap onto your feet and jump around on to have fun, if you’re, like, six years old, maybe? Anyway, if you happen to run into a pair of these, please be careful, and please think twice before doing something like, I don’t know, immediately strapping them on after you see them and jumping as hard as you possibly can, especially not when you are jumping on a hard unforgiving surface, or when you are surrounded by a bunch of impressionable children whom you could be concerned might follow your example or be swayed by your bad influence or something.

C/C++ to D

Wed, 14 Jan 2015 00:00:00 +0800

Some notes.

I’m assuming you want to use D largely, but not entirely, for competitive programming. That’s me right now.

Basics

Syntax is very similar. Function definitions, semicolon-terminated statements, variable declarations, and so on. You can declare int main() {...} or void main() {...} or something with arguments.

Basic types like bool and int and double are all there. Wonderfully, long is 64 bits. Instead of unsigned whatever, just prefix a u, e.g. uint.

Arithmetic operators and bit operators are all there too, including unsigned right shift >>>. Although ^ is still xor, D has exponentiation as ^^. Sadly, % is still same-sign remainder; there’s no true mod.

import std.stdio;

Casts look like cast(int) x;

Control Flow

if, while, for, do, and even switch all work as you’d expect, along with break and continue.

foreach is the nice addition though. Not only can you iterate over arrays and stuff, but range loops go like:

Rewind

Wed, 31 Dec 2014 23:59:38 +0800

As per item 3 of 50:

InfiniteLooper version

Well, there are better memory-triggering songs but I think this pretty much sums up how I feel about blogging right now (possibly including the very act of choosing that song.) And college apps. And life. Plus, the music video is silly in its own incredible way.

Anyway. Around this time a year ago, I made a post talking about how around a year before that,

I paused my participation in big high-school competitions, for a variety of reasons.

And then I rambled on life and programming competitions.

If you didn’t get it yet, this post so far has been written to meaningfully echo the last one. Nothing so abrupt has happened this year, but I just realized how nice it was to have a paragraph humorously listing the weird stuff I had gotten myself into over the course of 2013, so I’m going to do so again, even more completely.

College Questions (unprotected ver.)

Mon, 29 Dec 2014 19:54:05 +0800

This post, or most of it, was published password-protected once because… well, I explain that below. (To the one person who actually bothered asking me for the password, just so you know, I did add and rewrite parts. More than a few.) I forgot how distinctly powerful a disincentive a large 2300-word block of text is to the average person, especially when the subject of half of those 2300 words is teenage angst (I’ve already linked to xkcd 1370 in enough places so I’m not even going to embed it here) interweaved with an insufferable amount of rationalist jargon. This will probably filter my readership more than sufficiently already.

I have still decided to protect one detail of the thought process, though. But even after that, I guess I do care more about how many people read this than I do for most of my other posts, so here’s a primitive attempt to gauge interest; if you choose anything beyond the first choice, I would also appreciate if you leave a comment, even if you don’t think you have anything to add:

edit: This poll has been removed, it wasn’t very interesting anyway.

I haven’t posted for a long period again, but I don’t feel too bad about it.

Well, until I look carefully at my blog draft folder and remember that I have 90%-finished drafts about the two debate competitions I went to (November 2013 and March 2014), and winning the previous Mystery Hunt (January 2014), and my summer trip to Penghu (July 2013). Which will probably never get posted out of awkwardness.

Oops.

But I’ve been busy, completely righteously busy, with college apps to write and algorithm classes to teach and speeches to write and a math club to sort-of lead and all the typical homework besides.

And then (for those of you who don’t have me as a friend on Facebook) I got accepted to MIT and Caltech early.

And for a few days after that, I checked Facebook about sixteen times a day for the Class of 2019 group discussion, except for one day when I really needed not to, thanks to the power of committing to my HabitRPG party to do something. I am increasingly learning that procrastination is something that has to be actively and strategically fought. But that’s not what this post is about.

College.

HOJ 226: CP (中)

Mon, 15 Dec 2014 00:00:00 +0800

This post was written in Traditional Mandarin Chinese for my fellow competitive programmers in Taiwan.

題目在這裡，HOJ 226

有關的題目出現於NPSC 2014 高中組決賽pD。

前置要求：treap (split, merge)跟在上面實作區段操作（請參考資訊枝幹）。

這裡沒有完整的解答code，因為AC是要用血汗換來的才值得 :-)

Treap

我討厭單字母l的變數名稱（跟1太像了。我沒有被這個雷過，這只是自己對自己程式碼可讀性的要求），所以我的子樹叫做lc(left child)，rc(right child)。

struct Treap {
    Treap * lc;
    Treap * rc;
    unsigned pri;
    char val;
    int size;
};

int size(Treap * a) { return a ? a->size : 0; }
void pull(Treap * a) {
    if (a) a->size = 1 + size(a->lc) + size(a->rc);
}

Commemorating Obvious Milestones Involving Chronological Sustenance

Wed, 19 Nov 2014 00:00:00 +0800

Well, there had to be something here.

Unfortunately I don’t have time for anything more complex, so here’s a low-effort illogical puzzle for the occasion. (It has been testsolved, at least. Thanks, Yoshiap.) It also features a brand new category, so as not to distract the people on LMI.

If you don’t already know what occasion it is, it’s easy to find out by looking through my archives or possibly anywhere else I’ve left a trail online. Or you could solve the puzzle! (Or you could scroll down to read the solution!) If this puzzle had an answer, it would be a nine-letter word, although like most of mathematics, it’s less about the answer than about the path you take to get there…

2017 edit: A warning that this has somewhat linkrotted and is harder to solve, but theoretically still possible.

Extreme Value Theorem

Wed, 22 Oct 2014 00:00:00 +0800

original sillier post

The “Extreme Value Theorem”, according to my old calculus textbook (Larson, Hostetler, Edwards, 8th ed.), is “A continuous function defined on a closed interval attains a minimum and a maximum on the interval.” The calculus textbook continues,

Although [it] is intuitively plausible, a proof of this theorem is not within the scope of this text.

Of course Rudin proves this, but coming from an unrigorous calculus background, the required deductions span three chapters and are very hard to motivate. That’s probably because it proves things for extremely general objects.

In particular, I have no idea why the definition of “compact” is what it is: “a set for which every open cover has a finite subcovering”. Therefore, here’s a less general but more motivated proof, from the grounds-up.

Definitions

Real numbers are hard to define. We only need to know that we can add, subtract, multiply, divide, and compare them, i.e. they’re an ordered field, and that they have the least-upper-bound property. That is, if we have a set of real numbers that are bounded above, then the set has a least upper bound, a bound that “perfectly fits” the set. Precisely, the bound must be such that every element of the set is less than or equal to it, and no smaller value satisfies the same property.

Numbers

Mon, 20 Oct 2014 00:00:00 +0800

Continuing the porting of stuff from betaveros.stash, and adding more stuff. Mnemonic Here’s my mnemonic table for digits, inspired by an old Martin Gardner column. I wrote from memory the first 132 digits of 2012! correctly at IMO 2012 with this table. I had remembered more, but unfortunately, if I recall correctly, I confused myself over whether I had encoded a 5 or a 2 by the S of “nose”, because this is supposed to be more of a phonetic code than a spelling one — otherwise double letters would be confusing and lots of randomly appearing digraphs would be wasted, because English is weird.

[IOI 2014 Outtakes]

Sun, 07 Sep 2014 16:01:28 +0800

Miscellaneous observations that didn’t make it into a compelling narrative, sometimes because I have forgotten exactly when they happened, sometimes because I only remembered when they happened after blogging about it, sometimes because it just seemed too tangential, sometimes just because of the circumference of the mooooooooooooooooon! (That made no sense and I’m not going to remember what I’m alluding to in a few months.) During the first day a guy came into the secret computer room that the Taiwan team had concealed themselves in, saw us watching anime (SAO 2 among others), and innocently asked, "

[IOI 2014 Part 4] Shades of Xanthous

Sat, 06 Sep 2014 13:04:16 +0800

No, I didn’t forget. Not for one minute. I was doing homework. I am very happy because that means I was actually carrying out my priorities as I envisioned them. I’ve probably edited this post too many times, though. Meh. But it’s the first weekend after finishing summer homework, so here we go again!

Fun fact: This is by far my favorite post title in the entire series. Possibly in the entire history of this blog.

In the morning of the last day of official IOI activities, there were a bunch of cultural activities, e.g. writing Chinese characters calligraphically, doing tricks with the diabolo, or picking up beans with chopsticks, and noncultural activities, e.g. getting somebody to pour water into a cup on your head while he or she was blindfolded. Due to the last activity I got wet, but my shirt dried really quickly. And alas, even though I had taken calligraphy summer classes a long time ago, my calligraphy was awful — robotic, lifeless strokes without the right aesthetic proportions to make up for it. Blargh.

Anyway, lunch followed, and then it was time for the closing ceremony, in the same building as the other ceremonies and contests. Our team caught the ending song of in a Chinese musical being rehearsed as we walked into the auditorium. While we waited for everybody, we milled about waving flags that our various teachers had brought, including not only Taiwan’s flag but also flags of my school, thoughtfully brought by teachers who had volunteered. A little later our leader told us that all the leaders had discussed the matter during a meeting and decided that we shouldn’t bring any flags to the stage while receiving our medals, so we were going to have to make do with being patriotic and school-respecting off stage.

There were a few performances, including two aboriginal music performances and the musical we had seen rehearsed ealier, which was a fun rock musical rendition of some Chinese tale that seemed to have been sharply abridged, giving it the plot depth of a Wikipedia stub-article synopsis — a conflict, boy-meets-girl-and-falls-in-love, and a lamenting Aesop song conclusion with thrillingly vague general applicability. But the singing and counterpointing and atmosphere were good. I guess it was proportional to the relative importance of the performance to the closing ceremony. The program interleaved them with the long-awaited medal presentations: one round of bronze medalists, one round of silver, one round of gold.

Dum-dum-dum-dum, medals! The home team advantage was really obvious here; the cheering and the medal-presenter handshakes were both significantly more forceful for Taiwan’s medalists.

I think our leader made this. Thanks.

Naturally, after the normal medals had been exhausted, the three full scorers received bags with prizes that may forever remain unknown to my sorry self, as well as a standing ovation from everybody in the auditorium. The orchestra had been going through ABBA songs during the ceremony, and very considerately played “The Winner Takes It All” for this part. It was impossible not to mentally fill in the lyrics.

The winner takes it all
The loser has to fall
It’s simple and it’s plain
Why should I complaiiiiiiiin?

Speeches followed. Most were just average forgettable speeches, but Forster gave another speech that was somehow even better than the one he gave at the opening ceremony, with nonstop golden quotables such as:

[IOI 2014 Part 3] Games of Luck and Strategy and Really Weird Noises

Sun, 17 Aug 2014 22:11:28 +0800

Shamelessly getting unfinished business out of the way. Yup, that’s me.

Excursion Day 1. We traveled down to Yilan on a bus. I played guess-it with Paul.

I was quite surprised at myself for remembering this game, but I think it’s simple and little-known enough to be worth mentioning. Guess-it is a remarkably pure game of luck and bluffing from one of Martin Gardner’s columns, played with a small odd number of cards, e.g. the 13 cards of one poker suit. The cards are dealt evenly to players (who can look at them) with one card left over, which is kept face down; players take turns choosing one of two actions:

Name a card and ask the other player if he or she has it. These questions must be answered honestly.
Guess the left-over card. The guesser wins if correct; the other player wins if not.

Guess-it is not trivial because sometimes you should ask the other player if he or she has a card that you already see in your hand; otherwise whenever you answered “no” to a query you’d immediately guess that the asked card is the hidden one. It is actually a solved game in the sense that the probabilities of the Nash equilibrium strategy for when to guess and when to bluff have been worked out already, but they’re not simple probabilities by any means and humans are terrible randomizers anyway. A few rounds of it sure beats rock-paper-scissors. I was very amused to lose almost all our games with 11 cards but win almost all of our games with 13.

Okay, no more gratuitous narrative excursions into game-theory. The first stop, National Center for Traditional Arts, was a very laid-back culture place with old-fashioned retro shops and streets.

We watched a 3D glove puppetry (布袋戲) video, in the same session as a lot of the leaders.

[IOI 2014 Part 2] One Line to Solve Them All

Sat, 26 Jul 2014 23:49:14 +0800

I started trying to sleep at 9 the night before the contest, tossed and turned in bed until 10, then fell asleep and got up at 3:35 in the morning. Blah. At that point, I went to the bathroom and applied some chapstick before trying to go back to sleep until 6. After breakfast, I grabbed a few minutes of sleep on the bus to the convention center where our contest would be, then slept on a sofa outside the actual contest hall alongside most of the rest of our team as we waited for a very long time until it was okay for us to enter. Competitions really mess with one’s sleep schedule.

Then, much too soon, we could enter. Day 1 of the contest was about to start.

The laptops were as yesterday, although they were protected with a white screensaver that indicated my name and ID as well as a countdown to the start of the contest. I was glad to see that my mousepad and all my writing utensils had survived without me. Somebody had the sense of humor to project an online stopwatch with an animated bomb fuse onto the screens to indicate the remaining time, which, once again, there was a lot of.

I conferred briefly with Paul (TZW (alphaveros (?))) about vim settings for a bit, but there were still fifteen minutes left or so. I idly stretched, practiced typing my .vimrc on an imaginary keyboard, and watched as the US dude two tables to my left unplugged his laptop’s mouse and rearranged absolutely everything on his table using the surface under his chair as swap space. (Well, that was how I mentally described it at the time, pending further revelations. (hint hint))

Then it began.

[IOI 2014 Part 1] Everything is More Exciting with Lightsabers

Mon, 21 Jul 2014 17:31:10 +0800

Okay, I guess it was really naïve of me to suppose that I could get any considerable amount of blogging done before the IOI ended. Onward…

We left off at the end of the practice session. As if somebody were taking revenge against us for not having to suffer through any airplane trips, we were served a cold airplane meal for lunch.

Seriously, the box had a sticker that noted its manufacturer as something something Air Kitchen and another translucent sticker that badly covered an inscription saying the same thing in much bigger letters. It contained a cold apple salad, a cold chicken bun, a cold flat plastic cylinder of orange juice, and a package of plastic utensils that was exactly like the utensils that came with every airplane meal ever. I was disappointed, but at least the salad tasted okay, and I ate an extra one because two of my teammates volunteered theirs.

To pass the time, we played an extra-evil ninety-nine variant. Apparently this is a very Taiwanese game because lots of student guides were teaching their teams the game, although our special cards differ from the ones Wikipedia lists in a lot of ways and our evil variant created more opportunity for sabotage and counter-sabotage and bluffing. 7s are used to draw your replacement card from somebody else’s hand, and that person cannot draw again and will have one less card; aces are used to swap your entire hand with somebody else, who also cannot draw a card; small-value cards can be combined to form special values (e.g. play a 2 and 5 for the effect of a 7) but after playing a combination you can only draw one replacement card; and later, to speed up the game, we added a rule where all 9s had to be unconditionally discarded without replacement but would still get shuffled back into the draw pile. Players lose if it’s their turn and they have no playable cards, including no cards at all.

While we were playing and repeatedly reveling in everybody ganging up to beat the winner from the last round, an instrumental version of “You Are My Sunshine” played on repeat in the background for literally the entire time. It wasn’t a very good version either. If you didn’t listen carefully for the fade-out and few seconds of silence at the end of each loop, you’d think that the loop was only one verse long.

[IOI 2014 Part 0] Waiting

Tue, 15 Jul 2014 21:30:53 +0800

Yes, I know day 1 of the contest already ended and is probably a more interesting topic to blog about, but I finished writing this last night just before the internet was cut off to quarantine the contestants from the leaders, who received the problems and began translating them. I didn’t know about this until it was too late, which is why I’ve been waiting since yesterday to post this.

To provide a counterpoint to the last post, one of the many, many advantages of entering an international competition is that you get to meet a lot more people you already know, so there’s less time spent being socially awkward. While waiting for stuff to happen, aside from all the expected time spent with the Taiwan team, I also talked to, played games with, and otherwise entertained a whole lot of people I already knew, including my schoolmates (no less than fourteen of them were volunteers) and some of the college students who had shepherded us around during olympiad training.

Which is a good thing, too, because there was a lot of waiting.

First I waited for my teammates; my parents had decided to take me to the hotel (Fullon Shenkeng) directly, since I had a lot of stuff, and I had arrived early. This took about an hour, after which we had lunch. Then I waited for the hotel to give us our room cards, which took about five hours, after which we had dinner. Finally, at night, I waited for the Codeforces system tests. Very nerve-wracking. But I’m getting ahead of myself.

Advantage #2 of being the home team: you can talk to all of the organizers and volunteers fluently, so you can get them to help you more quickly. Although we waited for our room cards for an obscenely long time, I got the volunteers to replace my pinyin-name-card with a legitimate one that said “Brian” on it really quickly.

Unfortunately, after I talked to a few more people, it looks like they aren’t going to change my name in the database. So if anybody reading this chances to look at the IOI live ranking and is unable to find me, look for the first name “Po-En”.

[IOI 2014 Part −1] Prelude.hs

Sat, 12 Jul 2014 22:34:59 +0800

Indexing debates are boring. Especially when you can just flagrantly disregard all concerns about memory safety (because C++ never had any in the first place) and write int _array[100008], array = _array + 2; I do this alarmingly often; hence, the title. Hashtag firstworldanarchists. Three ± 1 cheers for Haskell arrays.

Anyway. One of the disadvantages of entering an international competition as the home team is a lack of time to completely absorb the idea that what is about to happen is a Big Thing. There was lots of time before the other international competitions I went to to spend uncomfortably on airplanes trying to adjust for the timezone difference.

Not so for a competition in one’s own country. Right up to the night before entering the hotel that marks the beginning of everything, I’m still at home, furiously refreshing the AoPS IMO fora and Facebook for news (!!!), lazily solving trivial Codeforces Div II problems with ~~pointless~~ point-free Haskell one-liners, and blogging. (There’s more, but I kind of want it to be a surprise.)

Anyway, let’s set the rules. Well, there’s only one, honestly:

#pyconapac2014

Tue, 20 May 2014 22:26:53 +0800

Late post. As usual.

It started with an online competition — write programs, solve problems, get points. I wouldn’t call the problems easy, but they weren’t hard either. So I solved all of them. To make it even less impressive, only about twenty people submitted anything at all.

But the result was just what it was: I ended up with a free ticket to PyCon APAC 2014.

I’d prefer a conference about a more functional programming language, but I’ll take what I get. Another adventure!

Rise from the Ashes

Tue, 29 Apr 2014 19:27:33 +0800

After the first stage of selection camp, I was very nervous because I was fifth place in a selection sequence that would finally result in a team of four.

I screwed myself over on the first mock test by committing to a bad implementation method on a problem that was hard to get points on. My method seemed simple, but the memory usage leaked out in a way that was confusing and hard to patch; unfortunately, I tried to patch it in increasingly desperate and convoluted ways rather than scrapping the method, and thus missed out on many of the points elsewhere.

During the second test I failed to read the last problem carefully and spent too much of my time on the second problem, once again missing out on a lot of relatively easy points. I had optimized and optimized and pushed my quadratic runtime down to linearithmic, which would allow me to get the points for the last subtask — or so I thought. But with 10 minutes left I had all but one testcase right, and after desperately rereading my code, I realized that I had a string comparison stuck in an inner loop that could make my runtime degenerate to quadratic if the input string had lots of the same digit. In order to have a solidly linearithmic algorithm, I would have to implement a suffix array. Ten minutes? I gave up. (The problem setters told me afterwards that hashing would have worked too; I didn’t think of that at all. Oops.) I spent the 10 minutes reading the last problem and still failed to read it carefully. So that did not go very well.

But, as the title probably gave away, during the third and fourth mock tests everything went much better than expected. :)

HabitRPG

Thu, 17 Apr 2014 19:04:12 +0800

HabitRPG: harnessing the addiction of web games with cheap leveling mechanisms to destroy bad habits, avoid procrastination, and improve your life. (Ironically, I discovered it on /r/InternetIsBeautiful.) These claims sound a bit hyperbolic, but they are actually working on me. Most notably: for the three days after I discovered it, most of which has been spent at IOI selection camp away from school and worldly concerns, I’ve only gone on reddit once — and only for about two minutes.

Puzzle 45 / Fillomino [No-Path]

Tue, 15 Apr 2014 08:15:37 +0800

As requested, a puzzle post! Straight from the WTF-variant department. Quite hard.

This is a Fillomino, with the additional constraint that for each polyomino, there must not exist a path (i.e. a sequence of cells, each orthogonally adjacent to the next) that includes each of the polyomino’s cells exactly once (and does not include cells outside the polyomino).

As a degenerate case, 1-ominoes are banned as well.

Adventures in Cabal Installations

Sun, 13 Apr 2014 15:51:16 +0800

First Google Code Jam!

The format of this competition, allowing us to run programs on our own machines, brought up a very interesting issue for me: what programming language should I be using? (I had had similar considerations for IPSC 2013, but GCJ’s problems are closer to the traditional ACM-ICPC style.)

The obvious choice is C++, the language I use for roughly every other competition, but its safety (or lack thereof) is not very appealing. I need speed, but not that much speed. Unfortunately I still haven’t gotten around to learning any other friendlier mid-level languages (on the list: D, Go, or Rust), so I have no close substitutes for C++ right now.

Python is certainly available for a reliable arbitrary-length integer type, if nothing else.

As for non-candidates, Java has BigInteger and memory safety, but all in all I decided the benefits are too minor and it’s too ugly without operator overloading. Scala is probably way too slow. So I don’t expect to be writing either language.

The only difficult choice I have to make is, of course, Haskell — which can be quite fast, even while it’s ridiculously type-safe and expressive and referentially transparent and easy to reason about, once you’ve:

figured out how to do the problem
scrapped step 1 and actually figured out how to do the problem functionally
gotten the thing to compile

Even if I can handle step 1, step 2 is by no means a simple task, as my struggle to implement a mere Sieve of Eratosthenes efficiently shows. That is fun, but not at all intuitive; I am doubtful I can do this under contest conditions. It is extremely difficult to transfer my skills in learning how to implement, say, a segment tree or treap into this language.

But! Google links to the programming language breakdown for 2010 Qualification Round as an example, and much to my surprise, Haskell ranks somewhere between sixth and tenth place in popularity (depending on what you sort by), so there are functional superprogrammers who can presumably do something like this.

As it happens, I ended up implementing all four solutions to the qualification rounds in Haskell, because of the relaxed time limit and lack of any involved algorithms and data structures. I think it was worth it.

Re-Re-Revisiting the SAT

Sat, 08 Feb 2014 00:54:03 +0800

First, I got worked up about the test. Then I got a score and ranted about it on this blog. (I’m still uncertainly hoping that didn’t come off as arrogant. Let me add, I did not get a perfect PSAT.) Then a friend pitched to me the idea that I write an article about it for my school newspaper, which I did. It was far too long. As if that weren’t enough, I then decided to examine whether the SAT was an accurate prediction of “academic ability and success” for my English research paper. Now I’ve come full circle to this blog, where I’m going to try to synthesize and conclude everything, free of the shackles of the research paper format, to allow me to move on with my life. This post contains bits lifted from all three essays and lots of new stuff; I’ve been editing it for so long that I feel like I have it memorized. Its word count is around that of the newspaper article plus the research paper, i.e. far far far too long.

But whatever, nobody reads this blog anyway and I have to get this out of my system. When I said I wanted to “move on with my life”, I really meant my winter homework. Oops!

Disclaimer: I am not an admissions officer. I have not yet even been accepted to a prestigious university (despite rumors to the contrary…), for whatever definition of “prestigious”, unlike some of the bloggers I’m referencing. So some of this is pure speculation. On the other hand, some of it is researched and referenced, and I think the pure speculation still makes sense. That’s why I’m posting it.

Okay, here we go…

Let’s start with the question of accurate prediction. The SAT is a useful predictor, but not as useful as one might assume. Intuitively, it ought to be more accurate than other metrics because it’s a standardized test, whereas GPAs other awards vary by habits of teacher and region and are hard to compare objectively. But as a study from the College Board itself (PDF) found:

the correlation of HSGPA [high-school GPA] and FYGPA [first-year GPA in college] is 0.36 (Adj. r = 0.54), which is slightly higher than the multiple correlation of the SAT (critical reading, math, and writing combined) with FYGPA (r = 0.35, Adj. r = 0.53).

Of course, that doesn’t mean the SAT is worthless, because combining the SAT score and high school GPA results in a more accurate metric than either one alone. But by “more accurate” I refer to a marginal improvement of 0.08 correlation.

The Sands of Time

Tue, 31 Dec 2013 18:33:17 +0800

Random video! Although I feel that I’ve heard it earlier, my first conscious memory of getting linked to it is from this post. At first I thought it would be the right background music for this post, but upon further reflection I think it mainly suited me while I was writing this post. Well, it’s topical if you mentally replace “day” with “year”.

Anyway. Around this time a year ago, I paused my participation in big high-school competitions, for a variety of reasons.

Firstly, I stopped attempting to make IMO both because I wouldn’t get that much from the training and because other people ought to have the opportunity. I was concerned that I might condition myself to only be able to do math with the short-term motivation of contests. Better to focus on college math and maybe some original research, I thought. During the year, I did lots of the former and very little of the latter. Meh.

As for the IOI, my obvious next target: I was tired of training and going abroad while paranoid about whether my immune system would hold up. I didn’t feel that the IOI was worth that. To some degree, I also felt burned out about programming. Long story short, my treatment should end soon, and learning Haskell completely resolved the burnout problem.

But the most important reason, I think, was that “high school was too short”. I started math competitions ridiculously early and didn’t spend much time exploring other interests. I thought I knew myself well enough that I could say I didn’t have many more interests at all, but I was completely wrong (psych nerds will reflexively note this to be the Dunning-Kruger effect). I coded lots in weird languages — Haskell, as mentioned previously, plus Scala, plus all manner of other magical command line tools. I wrote my first math problem and submitted it officially, picked up a new instrument, went to a debate competition, served as an unimportant tech guy for MUN, discovered and became hooked on Pentatonix, participated in three puzzle hunts in Australia and one in Massachusetts, figured out my rough political stance, rode a boat, got retweeted by @eevee and @Kyrgyzstan_News, increased my Neopets™ fortune by over 3400%, and lurked on FurAffinity a little too much.

But now, dear competition world, I’m back.

74 Days

Fri, 27 Dec 2013 18:14:21 +0800

I did it!

Okay, I got a 2400. Happy now?

Thu, 21 Nov 2013 22:59:07 +0800

Note from the future, 2017-11-25: I am fairly unhappy with this rant as it stands — it makes many points I still agree with, but it just sounds sooo pretentious — but it is one of very few posts to actually receive a link from an external post I’m aware of, so I am letting it stand for historical interest. I wrote this years ago; please don’t take it out of context.

I have to admit, I got unhealthily worked up about getting this score.

For the purposes of college, I only ever wanted a score that wouldn’t be a deal-breaker — anything above 2300 would be enough. Any other time I had left would be better spent in other endeavors. Such endeavors might help on the college app, but more importantly, I’d also get to enjoy them.

So why am I here? Partly it’s because my classmates got worked up about it. Somebody specifically requested me to post my score somewhere. And partly it’s because there couldn’t be a better way at the moment to establish my authority to (yet again) rant against standardized tests here.

Puzzle 44 / ???

Tue, 19 Nov 2013 00:00:26 +0800

Edit 11/19 7:23 AM UTC+8: Fixed some transcription errors on right: R4C17 is D instead of N, and R15C17 is G instead of E. Neither change should greatly impact solvability. Thanks to ksun for pointing out an error.

Logic puzzles are easy to construct if one doesn’t have some specific pattern or theme in mind. It’s just that, given the increasing number of constructors and puzzles with amazing themes, I don’t think it’s very meaningful for me to just construct more puzzles of the same genres by putting down clues randomly. That’s why, for my seventeenth birthday, I took the puzzlehunt route and made something without instructions that is not completely solved by logical deduction. Still, I’ve provided all the information needed to do this puzzle initially, so I hope my not getting the inductive bits test-solved can be excused.

Fiction

Sun, 20 Oct 2013 11:54:00 +0800

“I like fantasy books! I used to read a lot of Eoin Colfer.”

“What does that mean, used to? You don’t read anymore? That’s so sa-a-a-ad…”

Our teacher and I had this conversation during our first English class, and I realized I agreed with her. Well, no, of course I still read: news articles, r/AskReddit threads, and the books we get assigned in class. But not fiction, almost. As I later mentioned to my teacher, I followed Sam Hughes’ Ra avidly (something I highly recommend). That was it.

What does my present self still think of Eoin Colfer? Although I adored the Artemis Fowl books when I was younger, my interest faded, but not before I had recommended it to my sister. The conversation spurred me to get out the seventh Artemis Fowl book, which I had stopped reading halfway through a year ago, and finish it. It was still true that I didn’t like it as much, because I couldn’t feel the high stakes strongly in the book and I found that the joking asides compounded the problem. But a few days later, when we took a trip to the Taipei library, I found the eighth book and borrowed it, plowing through nine-tenths of the book before we left. The ending seemed to be happy but still felt counterintuitively poignant for me. In any case, I had closure.

So what’s the lesson? Authors vary in output too. I was naïve to suppose that because I found this book boring, I had outgrown all books that were even vaguely similar. In the same trip, I also borrowed a bunch of other random fantasy books, plus a realistic fiction book about a teenage pregnancy, just for kicks. It turned out to be surprisingly good. In a week, I read four books, cover to cover, despite a typical load of homework and chemo.

Any excuses I made before about not having enough time simply don’t hold water. Still, I have yet to figure out if this sort of reading is sustainable, because not every book is so engrossing. Far from it…

Puzzle 43 / Fillomino [Nonrectangular + Walls]

Mon, 30 Sep 2013 20:52:46 +0800

I’m extremely satisfied — a little incredulous, in fact — with how this puzzle came out. chaotic_iak labels it the “most ridiculous fillomino ever in history”. Apparently, it’s rather tricky.

ETA: Journalistic responsibility compels me to mention that chaotic_iak also added, “might be beaten later”. Oops?

This is a Fillomino combining the Nonrectangular (polyominoes can’t be rectangles) and Walls (polyominoes can’t span thick lines) variant rules. I think the first variant first came from mathgrant; I’m not as sure about the second, but they both appeared in Fillomino-Fillia 2, at least.

Write a number in every empty cell so that every group of cells with the same number that is connected through its edges is a shape that’s not a rectangle with that number of cells. In addition, cells separated by a thick border may not contain the same number.

Anesthesia

Mon, 19 Aug 2013 23:02:46 +0800

I couldn’t remember how long it had been since we entered the ninth floor. Somebody had covered the elevator area with cartoon animals and landscapes. Not surprising, since all the children’s wards were here.

Funny idea, that: I am still a child for medical purposes.

I was not sick. Not more than usually, anyway. I didn’t need to get an IV drip installed or even change into the patient uniform the first night. There was nothing to do or feel. No guilt or fear, unlike last time — this check-up had been scheduled for along time and served as a simple test to see how my bone marrow was doing. No annoyance, either, because I knew it mattered; but no apprehension of the results, or of the needles. You can never get used to the needles, but you learn to just accept them anyway. There is nothing to be done about them.

Who knows? The result could be something bad. But I know enough not to take this hypothetical seriously before it was anything other than hypothetical.

I slept, and dreamt of vomiting carrots.

Puzzle 42 / Fillomino [Greater-Than]

Fri, 19 Jul 2013 08:57:13 +0800

Oops, I forgot the “puzzles” category was semi-reserved for puzzles I constructed/wrote, because among other things an LMI bot is following it. Anyway, if this makes up for anything, I have a puzzle that I’ve procrastinated posting for very, very long.

This is a Fillomino puzzle. Inequality signs in the grid must be satisfied by the two numbers they touch.

Rankk Solving Statistics

Thu, 18 Jul 2013 22:43:21 +0800

Funny, I go on a trip to Penghu followed by a four-day science camp and also get dragged into drawing classes and some sort of movie advising joint, and this is what I decide to blog about.

Since it’s summer, I went back to Rankk and solved stuff. This is lots of fun if you’re good with computers, plus a little math, cryptography, and general puzzling. I’m still stuck on level 8… oh well. Since the levels didn’t seem very indicative of difficulty to me, I decided to do some analysis.

New challenges have been added to Rankk over time, so my metric of difficulty is the number of solvers divided by the time from release to now. Of course this is far from perfect; for example, a challenge’s author doesn’t always seem consistently counted as a solver, problems with lower numbers and problems that will help level up are more likely to get checked out by new rankkers, and so on. But this is just for fun.

Music

Sat, 22 Jun 2013 23:13:54 +0800

Isn’t it weird to suddenly talk about this topic?

I don’t think that I have ever talked about music any more than briefly in passing. It might be confusing to my finger quotes audience, and I worry I’ll seem inconsistent.

Well, a foolish consistency is the hobgoblin of little minds. If you wonder, “I didn’t know that you sang and played the piano, or you liked music in that way — or, at all…” please note that I didn’t know either.

Test

Sun, 09 Jun 2013 21:58:01 +0800

Parts of this (a majority of questions, I hope) are intended as satire. Other parts of this are silliness created to blow off steam from being coerced into spending nine unproductive hours. Still other parts exist simply because I wanted to have equally many questions per test. Also, 256th post w00t. (2019 edit: after the migration, this post count is wildly incorrect, but whatever.)

“Verbal Reasoning”

Directions: The questions in this test are multiple-choice. Each question has four possible choices. Read each question and decide which answer is the best answer. Find the row in your answer sheet that matches the number of the question. In that row, fill in the oval corresponding to the answer you selected.

Haskell and Primes

Sat, 25 May 2013 23:03:05 +0800

“I have been told that any encryption becomes safer if the underlying algorithm is maximally obscured, what is most conveniently done by coding it in Haskell.” – rankk

Functional programming is terribly addicting! Partly I think the completely different way of thinking makes it feel like learning programming, and falling in love with it, all over again. Partly there’s this evil sense of satisfaction from using $s (and later <$>s and =<<s and &&&s) to improve readability for initiated Haskellers and worsen it for everybody else. Partly it’s because Learn You a Haskell for Great Good! is such a fun read — there are too many funny bits to list but my favorite so far is when the author analyzes the first verse of Avril Lavigne’s Girlfriend.

Although I think my code in Haskell tends to be more readable than in other languages, code obfuscation in Haskell is almost natural: all you have to do is refactor the wrong function to be “pointfree”, which means that even though it’s a function that takes arguments, you define it without parameters by manipulating and joining a bunch of other functions. Example (plus a few other tiny obfuscations):

isPrime = liftA2 (&&) (liftA2 ($) (all . ((.) (0 /=)) . rem) (flip
    takeWhile [2..] . (flip (.) $ liftA2 (*) id id) . (>=))) ((<) 1)

QQ wordpress why no Haskell highlighting (Editor’s note from 2017: The migration should highlight this now!)

Also, for some reason, you can do this in Haskell:

ghci> let 2 + 2 = 5 in 2 + 2
5

(via Haskell for the Evil Genius)

Okay, but seriously now. I wrote this about my journey to learn functional programming in the programming babble post half a year ago:

The main obstacle I have is that it’s hard to optimize or get asymptotics when computation is expensive (a big problem if you’re trying to learn through Project Euler problems, particularly ones with lots of primes).

MUMS Puzzle Hunt 2013

Fri, 24 May 2013 21:44:24 +0800

So, I somehow managed to get 25 points all by myself in MUMS Puzzle Hunt 2013. Well, I pestered chaotic_iak a little with 3.3 Diagnosus (.html with animated .gif) but we still didn’t recognize all the Pokémon until hint 3, at which point Google sufficed for me.

This is nowhere near the top, but compared to the usual results of whatever AoPS team I form, it’s amazing. By far the best result of AoPS was on CiSRA in 2010 (46th with 58 points), before I discovered puzzle hunts in AoPS; unfortunately due to people getting older and the influx of younger and younger people to the fora, there are less possible teammates each year and they have less time, so here I am by myself. (Also I could have accepted an invitation from a guy in the some-form-of-Elephant team, but I figure if you can win two MUMS hunts in a row you don’t need any more people.)

All in all: Yay!

Puzzle 41 / Slitherlink [Clones]

Sat, 27 Apr 2013 17:27:26 +0800

I survived midterms.

This is a Slitherlink mutant. Draw a loop through adjacent vertices that cannot intersect itself. Each number indicates how many of the four edges around it are drawn. In addition, each pair of colored squares in corresponding positions (e.g. R1C1 and R6C6, R2C8 and R7C3) must have an equal number of edges drawn around them (i.e. if there were numbers placed there, they would be equal).

Example "BetaWorldProblems"

Sat, 20 Apr 2013 11:51:06 +0800

because my title needs to mean something. (note from the future: before late 2017, when I migrated to Hugo and GitHub Pages, the blog was called “BetaWorldProblems”.)

Φllotaxy

Thu, 04 Apr 2013 13:49:55 +0800

This is beautiful. Why do they have to make it sound all mysterious and difficult? That’s (the reciprocal of) the golden ratio, by the way. Transcript since the resolution is far from awesome: “Most angiosperms have alternate phyllotaxy, with leaves arranged in an ascending spiral around the stem, each successive leaf emerging 137.5° from the site of the previous one. Why 137.5°? Mathematical analyses suggest that this angle minimizes shading of the lower leaves by those above.

Puzzle 40 / Fillomino [Samurai]

Sun, 24 Mar 2013 00:03:13 +0800

Yeah, and there’s this. chaotic_iak rejected this variant for his February sequence in order to get consistent 7x7 dimensions, so I made one. It’s been about a month. I have no idea why I procrastinated posting it until now.

This is a Samurai Fillomino, which means each grid satisfies the constraints on its own. Write a number in every empty cell so that, in each square grid, every group of cells with the same number that is connected through its edges has that number of cells. Note that the two grids must contain the same numbers where they overlap, but the grouping should be considered independently. I’d explain this really carefully if it weren’t the main gimmick of this puzzle.

Google Reader Powering Down

Thu, 14 Mar 2013 20:35:09 +0800

Google just announced it’s shutting down Google Reader in three and a half months… I am participating in the friendly Reddit DDoS-hug of all the alternatives (list, but scroll around in the thread for a few more). Darn.

Puzzle 39 / Contact + Slitherlink [Antisymmetric]

Thu, 28 Feb 2013 21:38:54 +0800

Yay crazy hybrids! I guess this one is kind of hard.

Draw a loop through adjacent vertices that cannot intersect itself. For each pair of symmetrically placed numbers, one is a Slitherlink clue which indicates how many of the four edges around it are drawn, and one is a Contact clue which indicates the total length of all straight segments adjacent to it where segment length is always measured up to the nearest turns in the loop.

~~Please click on the image if it looks weird, which it very likely will.~~

(This was a WordPress bug that should no longer be relevant.)

Adventures in Scala Pseudo-Abuse

Thu, 21 Feb 2013 22:01:25 +0800

So, what have I been doing with programming recently?

Scala is an amazing multiparadigm programming language that runs on the Java Virtual Machine and interoperates with Java. I learned about it last time reading random articles on Twitter.

When I say “amazing” I mean “This is a language in which my code gives me nerdgasms every time I read it.” Wheeee.

Okay, it’s not perfect. People say it’s too academic. It has a notoriously complicated type system (which is Turing-Complete at compile time). Its documentation is a bit patchy too. For a serious introduction, the Scala website has plenty of links under documentation, and a tour of features. Somebody wrote another tour that explains things a bit more. So here, instead of introducing it seriously, I’m just going to screw with its features.

Example of freedom. Scala lets names consist of symbols, and treats one-parameter methods and infix operators exactly the same. The full tokenization rules are a bit detailed and I put them at the bottom of this post for the interested. This lets you create classes with arithmetic and domain-specific languages easily, but it also creates some silly opportunities:

scala> val * = 12
*: Int = 12

scala> * * * * *
res0: Int = 1728

Puzzle 38 / Contact

Sun, 10 Feb 2013 00:00:47 +0800

A Naoki Inaba (JP) type, as seen on Para’s Puzzle Site.

Draw a loop through adjacent vertices that cannot intersect itself; each number indicates the total length of all straight segments adjacent to it, where segment length is always measured up to the nearest turns in the loop.

Let’s see how well WordPress’s scheduling works again. Happy Chinese New Year!

Now on GitHub!

Sat, 09 Feb 2013 22:54:34 +0800

Yay? Right now I feel about this a lot like I felt about getting Twitter. Nobody I know personally is there, but all the “famous” “technological” people are, and something like 90% of the open-source projects I bump into are too. Just like Twitter, I barely know how to use Git either, but that’s okay. For version control I’m going all command-line now! Last time I tried to link stuff up with Eclipse everything exploded, but after I ran git init from the terminal this time, it’s highlighting things red and green everywhere like it’s suddenly begging me not to forsake it for the command line.

Pronunciation Stereotypes and the Uncrackable IPA Code

Thu, 07 Feb 2013 18:37:12 +0800

Note: I wrote this in 2013. It seems too irreverent in places when I look back, and not quite in the way that I’d like, but maybe it’s kind of amusing anyway?

Disclaimer: just because a significant number of people in group A (esp. of a certain race/ethnicity) also have quality B does not mean that (i) all or most people of group A have quality B or (ii) people of group A who do not have quality B are in any way strange or inferior.

In other words, stereotypes are stupid; don’t apply them to real people.

The stereotypical “Asian” (a person from “Asia”, a mythical faraway continent consisting of two countries, China and Japan) is too hard-working, gets disowned for any grade below an A, has infinitesimally thin eyeslits, and pronounces L’s and R’s identically.

jumps at opportunity to find and use .gif seen on Reddit without understanding any context

The internet says the L/R thing is mostly due to Japanese having only a single sound somewhere in between those two. Wikipedia has a page on Japanese phonology which seems to support this. Still, Wikipedia articles on phonology all consist of giving every sound a long incomprehensible name, such as the “apical postalveolar flap undefined for laterality” for the Japanese sound discussed above, and I’m not Japanese, so don’t take my word for it.

Mandarin Chinese (blatantly ignoring the myriad dialect variations) has a perfect L sound (ㄌ) and an R sound (ㄖ) that is only a little different. Of course, there are people who still pronounce them identically, but it’s not common — generally, the language teaches L’s and R’s well. Right?

Puzzle 37 / Slitherlink + Masyu

Thu, 24 Jan 2013 15:16:51 +0800

Nikoli Slitherlink + Masyu hybrid; I don’t know who first put them together but combinations like this aren’t rare.

Draw a loop through vertices that cannot intersect itself; each number indicates how many of the four edges around it are drawn; the loop must pass through all large dots, and it must go straight through white dots while turning either before or after (or both), while it must turn on black dots without turning either before or after.

Puzzle 36 / Fillomino [LITS]

Wed, 23 Jan 2013 18:29:00 +0800

mathgrant’s hybrid type: a Fillomino (write a number in every empty cell so that every group of cells with the same number that is connected through its edges has that number of cells) where each tetromino has had their 4s replaced by one of L, I, T, or S describing their shape, and they obey the rules of LITS — they can touch if they are not congruent, they must all be connected, and their squares cannot form a 2x2 block.

Hunter on Vacation

Wed, 23 Jan 2013 16:18:58 +0800

Faint rainbow

So winter vacation started and parents had planned a trip to southern Taiwan, to get closer to nature and walk around and stuff.

Also, the MIT Mystery Hunt, the absolute granddaddy of all the other puzzlehunts in terms of age, structure, and size, happened this weekend. Originally, I didn’t have a team and just planned to look at the puzzles after they got archived and ~~try solving some puzzles~~ read the solutions while constantly thinking, “How could anybody ever solve that?” Because of that, I wasn’t planning to even bring my laptop at first; then I could force myself to study some long-overdue ring theory during the nights. I was taken aback by a private message on Saturday morning from somebody with many different names inviting me to remote-solve for Random Thymes.

Me: !!!!!!!!!!

Similarity

Wed, 16 Jan 2013 22:57:48 +0800

Sometimes, a sentiment randomly appears in my brain. I wonder about it. There’s a draft I’ve worked on because I’m trying to get something out of my bubble. My emotions are confusing and they need to be released.

And after a few sentences, they’ve been released, but the post’s not out there because I want to polish it. First it’s just a look-over for typoes or grammar, then maybe I want to get the flow of the sentences right or cut down the embarrassing bits.

Then, on the third read-over, I don’t know why I’m writing it anymore.

Puzzle 35 / Double Back

Fri, 04 Jan 2013 22:42:10 +0800

This is another MellowMelon’s Double Back. Briefly, draw a closed loop through all square centers visiting each bold-outlined area twice. Shaded cells do not influence solving, only aesthetics.

It’s mostly easy, I think. It’s okay if you don’t know what the theme means. (Yes, chao, I want more contrib points.) Also, WordPress seems to have stopped automatically linking images to their files. Hmm.

Puzzle 34 / Snail's Nest

Tue, 18 Dec 2012 22:08:43 +0800

It’s been a while, hasn’t it? This is something I constructed semi-experimentally to stop failing at an entire genre of puzzles, and then procrastinated posting just about forever. I only test-solved this on paper; I hope I didn’t do anything silly while digitizing.

Rules paraphrased from USPC because I can’t find any good links: Write each of the given words into its own snail; letters must be entered from the outside of the snail spirally inward. Not all squares will be used; squares with “-” must stay blank. Each letter can appear at most once in each row and column.

Ridiculously Long-Winded Programming Babble

Sun, 16 Dec 2012 22:08:28 +0800

Okay I don’t actually know how this pointless rambling got so long. I know the longer it is the more people will just tend to skim, because I do that all the time. So I went back and refactored—er, rewrote all the somewhat tangential bits (wow these puns are too easy) into footnotes. Manually. Obviously if I have to do this again I’ll write a script for it. But the post is still really long, and I bet nobody will read the whole thing. Oh well.

Life updates: I got out of the hospital Friday two-and-a-half weeks ago, went to the preliminaries of NPSC (a national team programming contest) with classmates, threw up a lot, went back into the hospital, and came out again. I wrote a lot of stuff about the experience and how much it sucked (hint: a lot) when I started this draft around that time, but now putting so much detail in this post feels weird. I’m mostly good now.

Three years ago NPSC was the only programming contest I really knew of; now I’ve participated in quite a few more, both online and locally, but it’s still the only contest I’ve entered that gives you real-time verdicts. I believe it inherits this from being modeled after ACM-ICPC, but that’s for college people and I’m less clear on how it works. All the other contests, namely TopCoder, CodeForces, USACO, and the other local individual competition (there doesn’t appear to be an English name so for the purpose of this post I’ll just call it “Nameless Local”; there’s a nation-wide competition in one-and-a-half weeks!), have system tests after the contest that don’t allow you to resubmit afterwards.¹ They all give pretests that you get to know about right away, just to catch super-silly non-algorithmic mistakes like failing to remove the debug statements or reading input from the wrong place, but these contain weak test cases and don’t guarantee that the solution will pass the system tests and get full score.

Gridderface 0.5

Tue, 27 Nov 2012 17:53:13 +0800

Okay, I give up. Here it is: Gridderface is a (quoting the project description, which I wrote anyway so whatever) “keyboard inferface for marking grid-based puzzles in Java” that I’ve been working on for too long. It is open-source under the GPL v3. Basically, it’s a thing you can paste logic puzzle images into to solve them in, like people do in Paint, when you can’t or don’t want to print them.

Puzzle 33 / Ice Barns

Thu, 22 Nov 2012 20:59:38 +0800

Noticed this at meander lawn who has a really broad puzzle blogroll… I don’t really know what I’m doing and may have misinterpreted something, but here goes. (Ahahaha puzzle 33 on 11/22… I wish it was intentional :P)

Draw a path through square centers which enters and exits through the given places. Outside the “ice barns” (the gray things), the path may turn freely but may not self-intersect; inside “ice barns” the path may self-intersect but may not turn. Each ice barn (not necessarily every cell but every region, I think) must be passed over. The path must pass through each given arrow in the given direction.

Puzzle 32 / Slitherlink [Crosslink + Liar]

Mon, 19 Nov 2012 00:00:44 +0800

Yes, a “big” crazy mutant puzzle for a “milestone” (as seen on xkcd), both for this blog and for my life. Things are rough now, but I prepared this ridiculously ahead of time. It’s still not really big, but I’m not so experienced and I don’t have the inspiration for something like an entire mini-puzzlehunt. Also, I think I should attempt more word-bank-based puzzles some day so I won’t fail as completely at them.

But anyway: This is a Slitherlink combining MellowMelon’s Crosslink and Liar variations. Draw a loop through vertices that can intersect itself but must go straight both times if it does; each number normally indicates how many of the four edges around it are draw, but exactly one clue in each row and column is false. Have fun.

Puzzle 31 / Fillomino [Sashigane]

Fri, 09 Nov 2012 17:03:16 +0800

This is a Fillomino puzzle where every polyomino is required to be an L-shape, as in Sashigane. Write a number in every empty cell so that every group of cells with the same number that is connected through its edges is an L-shape (with arms of positive length and 1-cell thickness) with that number of cells.

My second, and now symmetric, attempt at this crazy self-invented mutant; puzzle 22 was the first. A word of warning: I can’t solve this without bifurcating near the end, so logic purists may be disappointed, but I like the clue arrangement too much. In fact I suspect this puzzle could have many more clues removed without affecting uniqueness, so tight are the rule constraints in this type.

Puzzle 30 / Fillomino [Skyscrapers]

Fri, 09 Nov 2012 16:58:09 +0800

Haha, way-overdue Fillomino-Fillia practice puzzle. This is a Fillomino puzzle; in addition to normal rules, treat numbers inside the grid as building heights. Numbers outside the grid indicate how many buildings can be seen from that direction, where a building blocks all buildings of lower or equal height behind it.

Edit: I should warn that the arithmetic here is pretty annoying.

Puzzle 29 / Corral [Antisymmetric Multiplicative]

Thu, 08 Nov 2012 17:35:43 +0800

This is a Corral puzzle in which half the clues are multiplicative. For each symmetric pair of clues, one is normal and one is multiplicative.

Adventures in Meta-Debugging

Mon, 05 Nov 2012 22:28:39 +0800

Okay did I mention how I sucked at the command line? This is part of the journey towards stopping. Yes, I’m on a Mac and it’s not very *nix-y in some ways but it’s enough for me for now.

Today’s story starts when I learned about gdb, the pure-command-line GNU Debugger, which is incredibly cool. I have tried and failed to learn how to use the debug function on many of my IDEs; I found shotgunning printf statements as needed faster. This may well be the first time I found a command-line tool so much more intuitive than the GUI-equipped programs. Wow.

Then I learned that for some reason the gdb on this computer was 6.3, which is 1.2~1.5 major versions behind (depending on how you count) and missing a frustrating amount of features. (The one that the current Code::Blocks installer installs is also something like 6.4. Blech.)

Unread Count

Sat, 03 Nov 2012 11:32:50 +0800

Note from 2019: My 2012 self wrote this. I don’t remember writing it. This is the first time I have felt personally attacked by a post I wrote seven years ago.

Why do so many people have these three- or four- or even five-digit inbox unread counts? I become uncomfortable when I have more than about five unread emails, or if there are twenty emails of whatever status in my inbox — the rest get archived, of course. Out of sight, out of mind. Whew. It’s hard for me to fathom how anybody can sleep knowing they have such a scary number of unread emails waiting for them.

Why does the status of being unread matter, one might ask? There are already so many ways to classify things in the typical inbox: stars or labels or folders or flags or whatever your mail service may call them. Well, the thing that makes the unread qualifier stand out is that it already has meaning; you don’t need to assign it any. It means you haven’t read it! Thank you, Captain Obvious.

If you know how to use email, there are no good reasons to ignore the status. Is the email actually not important to the point where you won’t even bother to read it? In that case, why is it even in your inbox? If it’s spam, mark it as such; spam filters are pretty effective nowadays, but only if you train them, and even if not it only takes one click to get rid of it. If it’s some notification you don’t care about, unsuscribe or fine-tune your subscription. As invasive as web services are getting nowadays, I haven’t yet seen a legitimate one that doesn’t provide a link to let you do one of these things, even if it’s concealed in small gray text at the bottom of the email. Should you encounter a notification that doesn’t have these links or doesn’t stop spawning evil clones after you tell it to, don’t think twice; it is spam and should be mercilessly filtered as such. And if you still have two hundred emails left after all that, you should either rethink your values or start reading them now.

Puzzle 28 / Fillomino [Nonrectangular]

Wed, 24 Oct 2012 20:39:47 +0800

This is a Fillomino puzzle where every polyomino is required to be nonrectangular (which also bans squares). Write a number in every empty cell so that every group of cells with the same number that is connected through its edges is a shape that’s not a rectangle with that number of cells.

Fillomino-Fillia 2 is coming! Anyway I don’t know how to judge difficulty but this is probably terrible practice. I should try a Skyscrapers if I can keep pretending USH homework doesn’t exist which I probably shouldn’t.

Puzzle 27 / LITS

Tue, 23 Oct 2012 19:37:35 +0800

Nice and tricky. (I think.)

In fact I tried to be too tricky and spent a very long time fixing an ambiguity. It was worth it though.

LITS - Nikoli. Exactly one tetromino per region, no 2x2s, they’re connected, adjacent tetrominoes are noncongruent.

Matrix Intuition

Sun, 14 Oct 2012 17:01:29 +0800

Stopped by a friend’s house a few days ago to do homework, which somehow devolved into me analyzing what programming language I should try to learn next in a corner, which is completely irrelevant to the rest of this post. Oops.

Anyway, in normal-math-curriculum-land, my classmates are now learning about matrices. How to add them, how to multiply them, how to calculate the determinant and stuff. Being a nice person, and feeling somewhat guilty for my grade stability despite the number of study hours I siphoned off to puzzles and the like, I was eager to help confront the monster. Said classmate basically asked me what they were for.

Well, what a hard question. But of course given the curriculum it’s the only interesting problem I think could be asked.

When I was hurrying through the high-school curriculum I remember having to learn the same thing and not having any idea what the heck was happening. Matrices appeared in that section as a messy, burdensome way to solve equations and never again, at least not in an interesting enough way to make me remember. I don’t have my precalc textbook, but a supplementary precalc book completely confirms my impressions and “matrix” doesn’t even appear in my calculus textbook index. They virtually failed to show up in olympiad training too. I learned that Po-Shen Loh knew how to kill a bunch of combinatorics problems with them (PDF), but not in the slightest how to do that myself.

Somewhere else, during what I’m guessing was random independent exploration, I happened upon the signed-permutation-rule (a.k.a. Leibniz formula) for evaluating determinants, which made a lot more sense for me and looked more beautiful and symmetric

\[\det(A) = \sum_{\sigma \in S_n} \text{sgn}(\sigma) \prod_{i=1}^n A_{i,\sigma_i}\]

and I was annoyed when both of my linear algebra textbooks defined it first with cofactor expansion. Even though they quickly proved you could expand along any row or column, and one also followed up with the permutation formula a few sections later, it still felt uglier to me. Yes, it’s impossible to understand that equation without knowledge of permutations and their signs, but I’m very much a permutations kind of guy. Sue me.

Puzzle 26 / Double Back

Wed, 10 Oct 2012 08:48:10 +0800

That’s not a picture. Why is it recreated as one? Oh well.

You can interpret this as me about reaching level 8.1 (the user ranking) on rankk or complaining about how infuriating level 8.1 (the puzzle) is. I’m torn.

This is one of a bunch of MellowMelon’s Double Backs. Briefly, draw a closed loop through all square centers visiting each bold-outlined area twice. Shaded cells do not influence solving, only aesthetics.

Puzzle 25 / Double Back

Wed, 10 Oct 2012 08:40:02 +0800

Most uncreative picture ever! But it’s suitable after CiSRA’s Puzzle Week. This might be the first time our AoPS team managed all four puzzles in a group.

…sigh, now I must handle the guilt for squeezing out so much time from my normal schedule.

Puzzle 24 / Double Back

Wed, 10 Oct 2012 08:26:11 +0800

Right, back to puzzles because I have nothing substantial to say. Circumstantial evidence suggests I created this one in June.

This is one of a bunch of MellowMelon’s Double Backs. Draw a closed loop through all square centers visiting each bold-outlined area twice.

Puzzle 23 / Corral [Multiplicative]

Wed, 19 Sep 2012 21:49:01 +0800

Too lazy to explain rules today although this is probably an easy one.

Comments

Wed, 19 Sep 2012 18:46:21 +0800

Note: My 2012 self wrote this. It is a little dated and does not entirely capture my current beliefs and attitudes, although I have to say it’s not too far off either. As of 2018, Me and Facebook is more relevant.

Here’s a guilty secret: I like getting feedback.

I’m not restricting myself to painstakingly thoughtful comments that attempt to build upon and transform the post to form an interesting conversation, the kind English teachers are hellbent on promoting. Sure, I get the most kicks out of those, but I’m not picky. Even single-digit pageview bars or a handful of Facebook “like”s give me buzzes of excitement.

It’s a guilty feeling, because I also think that that these are unimaginably cheap internet currencies and should not qualify as “meaningful” under a rational mindset. I strongly suspect visitors accidentally click on my blog and leave after five seconds without taking in anything, because I do that all the time to other people’s blogs and sites. Sometimes it is out of boredom, sometimes it is because I actually have something of higher priority to do than indiscriminate reading, sometimes it is simply because I cannot read the language. I’ve seen plenty of people like posts on Facebook based on the poster, only occasionally taking into consideration the first word of the post in question, before actually reading them.

Yes, the proliferation of “liking” on Facebook bothers me. I don’t expect everybody to reply meaningfully to everything when they just want to express approval lightly. However, when I see that tiny minority of people handing them out to people in their own threads like programs at a concert, I become indignant. Under their influence, what was originally a straightforward, meaningful badge of appreciation becomes a handwavy gesture that carries virtually no weight, and then I don’t know what to do when I see something I like seriously. Will clicking that button still express the feeling strongly enough?

I accept that, in our stressful world, a few instant effortless gags that take ten seconds to fully process and approve deserve a place. Nevertheless, the number of people who seem to want to make the “like” a completely passive and automatic action is almost physically painful:

Puzzle 22 / Fillomino [Sashigane]

Mon, 10 Sep 2012 21:07:31 +0800

May be slightly reminiscent of no-rectangle Fillominoes. Slightly… (Has anybody done this before? It seems so interesting that I feel like I couldn’t be first.)

[IMO 2012 Part 6] Mostly Not About Excursions

Mon, 27 Aug 2012 08:40:00 +0800

Yes. I know it’s been more than a month. Blogging motivation decreases, but the responsibility of that stay tuned doesn’t go away.

It’s okay. It’s all worth it because the stuff in the games room is absolutely ridiculous. Warning: huge post.

Our old friend, the monster of a functional equation, in edible form. In the games room. Did I mention abso-zarking-lutely ridiculous?

Puzzle 21 / LITS

Sat, 25 Aug 2012 10:27:40 +0800

I made this a long time ago but put it off until I had programmed enough to digitize it without my fingers leaving the home row. I think the finish is interesting.

LITS - Nikoli. Exactly one tetromino per region, no 2x2s, they’re connected, adjacent tetrominoes are noncongruent.

Puzzle 20 / Sashigane

Wed, 22 Aug 2012 07:12:36 +0800

Yeah, I lied last time I made one of these; the original Nikoli name wasn’t that hard to remember, and “sashigane puzzles” has shown up as a search query, so here you go. Perfect opposite-type-clue rotational symmetry, chaotic_iak! I hope you’re satisfied now.

On writing

Mon, 20 Aug 2012 13:34:15 +0800

Note: My 2012 self wrote this. It’s a bit dated, but it’s okay, and also is of historical interest for featuring me explaining the CSS I learned from English class.

Every time I notice that I have hoarded a large number of strange assignments and essays from another school year of work I get all guilty. First there’s the knowledge about ancient Chinese dynasties and plant hormones that I only have shadows of recollections of, which makes me wonder whether all the time and effort invested by teachers, classmates, and myself have gone wasted.

I know, though, that given that I still sense these shadows, it shouldn’t be difficult to look up and relearn this stuff if I ever need to do so. This brings me to the non-factual parts of the learning, such as writing skills with all its variations. There’s persuasive writing, which I don’t use much because I can’t usually even persuade myself to take a side in anything, let alone others. There’s descriptive writing mode, which I don’t use much because the most vividly describable things I encounter are food, and the shallowness of piling flowery adjectives together to talk about food just makes me cringe nowadays. Previously, I wrote at least two such compositions in sixth grade. Blech.

[IMO 2012 Part 5] Unlucky Fours

Thu, 02 Aug 2012 23:03:41 +0800

[edit: okay guys I’m surprised at many people come here with search queries looking for solutions. If you want IMO solutions, the corresponding AoPS forum invariably has many of them. This is probably late-ish, but just in case.]

Day 2 of the contest.

Did you know that in Chinese [or Mandarin, whatever] “four” is unlucky because it’s a homophone for “death”, and hospitals tend to skip it in floors or ward numbers?

Did you know that there was going to be an anecdote involving the seventh Artemis Fowl book but I couldn’t make it work so instead you have a weird and utterly disconnected metareference to something deleted?

I don’t know, it sounded cool at the time.

Problem 4. Find all functions f: Z → Z such that, for all integers a,b,c that satisfy a+b+c = 0, the following equality holds: \[f(a)^2+f(b)^2+f(c)^2=2f(a)f(b)+2f(b)f(c)+2f(c)f(a).\] (Here Z denotes the set of integers.)

An innocent-looking functional equation, but once you start trying it you discover that there’s quite some depth to it. Random guessing can yield that $f(x) = x^2$ is a solution, so I proved inductively that after dividing out a constant f(1) then the remaining part of f is a perfect square. Letting $f(x) = f(1)g(x)^2$ with g(x) a nonnegative integer and factorizing the original equation, I got an auxiliary functional equation equivalent to the original equation.

Casework on small values of g, and the surprises started coming hard and fast. First: wow there’s an extra odd-even solution! Then: woah there’s another mod 4 solution! What is this madness?

Puzzle 19 / Yajilin

Thu, 02 Aug 2012 14:16:36 +0800

I have just realized that I have only ever tried one level of difficulty in puzzle construction, viz., “as hard as I can make it”. This is mainly because I don’t want to construct anything overly trivial with the same few tricks, but, well, maybe it’s not the best idea for actually trying to build an audience.

Am I actually trying to build an audience? Am I? *shudders*

(Yajilin summary: fill in some cells, draw a loop through the rest, filled cells aren’t adjacent, arrows denote # of filled cells along some ray; MellowMelon’s rules)

[IMO 2012 Part 4] The Inequality of Broken Dreams

Thu, 02 Aug 2012 11:07:33 +0800

I could spend all day coming up with post titles like this one. Really, I could. Anyway, after receiving the letter gently reminding me to turn in the official IMO report in Chinese, I finished that first and turned it in. This, plus the fact that I don’t have any way to do any of my summer homework yet, should make continued blogging much easier.

These months of preparation and anticipation, and in just over two days it will be behind us forever.

Thus were my thoughts at 3:30 in the morning, which were a much worse method of preparation than that which I used for the APMO, which involved trying for the first time to put my compass in its box and staring at a cryptic crossword. Twisted thoughts as I lay innocently in bed, trying to preserve my spirit and mathematical function. I got up at 6:30 and ate a breakfast nervously with the team.

We dispersed into the contest hall. Flat squarish white tables in orderly rows greeted us. They were considerably smaller than the arm-span tables we had last year in the Netherlands’ stadium, but the space was still ample compared to the ones we took our practice tests on at home. I floundered a bit looking for whoever was supposed to check our stuff for forbidden items, but none of the proctors paid any attention to that, so I flipped through my own jacket pockets paranoidly.

But preparation was too brief, and there were at least fifteen minutes left with nothing to do except try not to panic. I managed to fill these fifteen minutes by doing elaborate breathing exercises, raising and flapping my arms, counting down seconds, focusing on a color word, meditating badly, clearing out everything nonmathematical from my mind with a symbolic gesture. This is not a very coherent description, but I wasn’t feeling very coherent.

I opened an eye halfway and watched as the clock ticked down the last few seconds. The starting signal sounded. I opened up the problem envelope…

Puzzle 18 / Smullyanic Dynasty

Wed, 01 Aug 2012 19:03:44 +0800

Again, the Zotmeister type. (Short rules: each cell states how many liars are in the 3x3 square centered at it, liars incorrectly so. Liars satisfy the “dynasty” rule i.e. liars are not orthogonally adjacent and non-liars are connected through sides.)

Puzzle 17 / Corral

Mon, 30 Jul 2012 19:07:41 +0800

Corral puzzle, aka Cave aka Bag etc. (Yes, from nikoli.) Short rules: draw a loop along the grid lines; each numbered cell is in the loop and the number denotes how many cells can be seen vertically or horizontally from that cell, plus the cell itself. Stealing link to MellowMelon’s long rules.

[IMO 2012 Part 3] Luggage Carriers and Language Barriers

Wed, 25 Jul 2012 09:32:45 +0800

Who knew coming up with strangely cryptic and illogical but nice-sounding post titles was so much fun!?

Okay, this break in storytelling is mainly brought to you by generic summer laziness, as well as possibly a tiny bit of chemotherapy adverse effect. There is only a little perfectionism involved, and that’s because this post contains a long awkward situation (you might have guessed already). I guess this is what it feels like to have oodles of stuff to blog about, but not enough motivation. Heck, these few days with running the TAIMC have long filled my list of rant topics with juicy stories until it’s near-bursting. But I need to end this self-pity party before I get carried away, so… back to the action.

Stranded in a foreign country at least 20 degrees Celsius below our comfort zone, having worn the same clothes for 36 hours of airplane travel, and still with less than 48 hours until the contest and zero out of six compasses, we were running out of options.

A quick inventory of clothes showed that, after including the vests and caps in the backpacks we got, we probably had just enough clothes to survive the cruel frigid environment. So, reluctantly, we left the games room and hit the street to hunt down some underwear and socks to change into. Not to mention toothbrushes and some T-shirts and jackets for good measure, because the inside of the hotel was not the right temperature for full cold-resistance gear.

Some haphazard wandering up and down the streets later, we found a store that suited our needs and picked up some clothes. The underwear came in two sizes: too loose and too tight. We picked the latter. Oh well, it would only be for a day or so… right?

[IMO 2012 Part 2] The Hotel of Deception

Fri, 20 Jul 2012 12:45:41 +0800

We finally arrived at the hotel at 3:30, meeting another local from Taiwan, Mr. Chen, who helped us carry some of our stuff off the bus. Po-Chiang, our guide, was waiting inside. We took more pictures and finally lugged the meager stuff we had off to our hotel rooms.

At least, we tried. I started to realize that there was much more to this hotel than it seemed.

Firstly, of course, was the confusing placement of rooms with numbers starting with 4 and 5 on the fourth floor (which would be the fifth floor by our numbering system, where the lobby is floor 1; but here the lobby was assigned 0. Off-by-one errors just waiting to happen here.) Secondly were the completely indecipherable signs. I don’t remember the details, but the first signs we saw read something like “560 ~ 540: left; 520 ~ 540: right”. Occasionally there would be weird slashes or half-slashes between the numbers instead (later I finally realized they were slanted, Comic-Sans-style capital Ys, or “and” in Spanish). Are these closed, open, or half-open intervals? And why the heck are their upper and lower bounds in a different order!?

We wandered through the corridors, peeking down each one, trying to figure out whether the numbers were increasing or decreasing and whether a parity argument (for those of you not fluent in math lingo, that means odds and evens) allowed for the existence of our room. Who knew the simple act of finding one’s living quarters could be so mathematically tasking? In the end, our rooms were in the last corridor, just about diametrically opposite to the elevators on the half of our floor. Oh well.

The room was pretty nice overall. The furniture and basic facilities were quite complete, with a sparkly bathroom and a couple tables and chairs of various shapes. The closet was big and had a safe, which was rather important because just about everybody we had met had warned us over and over again about all the incredibly skilled thieves, muggers, and pickpockets in Argentina. It was probably much safer (no pun intended) in the hotel, but with all of these warnings (later we would even find a notice from the hotel warning us to lock our doors) I was never entirely certain. There were lots of lights controlled by a set of confusing switches on either side of our beds. There was at least one white immovable divider cunningly disguised as a switch, one switch that didn’t ever seem to do anything, and one that turned everything off. The last one made a little sense after a while because it had pictures of stars and a moon on it, but the whole setup was still pretty non-user-friendly in my opinion.

[IMO 2012 Part 1] Dangerous Metal Chopsticks

Fri, 20 Jul 2012 07:44:51 +0800

It’s time to begin the epic blogging journey. The detailed version of this year’s amazing IMO, because I decided that a perfectionist guy like myself could not possibly liveblog and be satisfied with both the quality of the posts and being able to fully enjoy the actual event.

Our story begins in a hotel in Taiwan.

The night before departure, us six contestants and Prof. Lin gathered in a hotel. This was entirely necessary because our flight left at something like five o’clock in the morning. After checking over the flight plans and relevant phone numbers in a conference room, we enjoyed a pretty extensive buffet dinner, what would easily be the best meal we would get to have for at least a week, the highlight of which was a fish steak that looked and tasted exactly like fried egg. Afterwards we did some emergency shopping and prepared a convenience-store breakfast for consumption three o’clock the next day.

As I’ve complained before, we have an 11-hour difference to get used to, and that morning I had gotten myself to sleep as late as 6 AM trying (successfully, much to my amazement) to complete an iPod OS system update. I didn’t think I could pass airport security with the sort of consciousness I had when I finally slept that morning, so I reverted with the rest of the team to an 11 PM curfew. Oh well. The seven of us left the hotel after 3 AM, setting off in a huge 30-person bus for the airport.

Luggage drop-off was mostly uneventful. I realized that the airline didn’t seem to like passengers bringing two bags onto the airplane, and decided to distribute my bag with all the winter clothes in it into my luggage and my backpack. Little did we know what would happen to the luggage…

Glowstick Memories

Thu, 28 Jun 2012 22:37:50 +0800

So. It looks like I’ve officially graduated.

I have to wonder whether it really means anything. Taiwan’s system classifies the grades neatly into 6/3/3 sections, but then our bilingual department also uses the somewhat illogical and faintly sexist freshman-sophomore-junior-senior naming thing, in which the big jump happened last year.

Neither of these naming issues, of course, really matter. Shakespeare says, “A rose by any other name would smell as sweet.” Nor, I would think, do the different color of uniforms we have to wear (pink, if you didn’t know.) But AP classes probably count for something.

I am going to take AP Biology. Why did I pick AP Biology anyway? It seemed like a reasonable default choice. I guess I would like to know something more about the mysteries of life and consciousness to guide my philosophical side, and many of the other courses looked too murderously intense. The perfect stepping stones into the giant hamster wheel of overachievement that everybody is crazy about here. But then I learned I still received eight chapters to study by myself during summer vacation, alongside the English reading assignment. Oh well, so much for relaxation.

You know, I used to think of this issue, about all the academic work we students pile onto ourselves and all the ensuing stress and chaos, from a strange detached third-person viewpoint. Not everybody has a mind that is fit for all that brainwork. Some people have to do the artistic, imaginative things. Some people cannot function optimally in our intense learning environment. Somehow, imperceptibly, according to my apparently not-all-that-bad grades, I put myself in the crazy book-grinding category, and I am having second thoughts.

I don’t feel the energy for all this intense future yet… The past is still so close, so vivid, so attractive. Our graduation trip, for instance.

Yeah, okay, fine, I admit it, what follows is a rough record of our graduation trip that has been stuck in draft limbo for approximately forever, and I was trying to segue into it. I’m a perfectionist, what can I say?

Impact Minus Two Weeks

Mon, 25 Jun 2012 20:14:12 +0800

Wait, are you serious? Under two weeks left, is that what it’s come to?

What happened to my majestic plans to go over every functional equation I failed on, ever? Or to go through a super-intense geometry-immersion period and actually try to develop some of that crazy “intuition” thing? And I have finals coming up too! I just finished a ludicrous deadline-extended geography project that I am absolutely confident is the crappiest paper of my entire school career so far! And despite a semester of (slacking) classes, my Spanish is still only barely at a usable level! Exclamation marks!

Don’t panic… let’s focus on the positive. I am absolutely prepared with my stationery. I bought three spanking new 0.4mm pens that say “Can write for 1000 meters!” because all of my current ones are annoyingly thick and constantly having almost-but-not-quite run out, plus three new mechanical pencils and enough matching 2B lead to last me through college. All the pencils and lead are Pentel. I haven’t done any research, so if something terrible happens in Argentina I know what company to blame, and I am writing it here so I won’t confuse the brands. Also, in view of what happened to SCH’s carry-on baggage last year (luckily there was no geo on Day 1), I got an extra compass I hope won’t be needed.

While we’re listing all the stuff I have gotten ready:

Puzzle 16 / Slitherlink [Domino]

Wed, 06 Jun 2012 19:57:09 +0800

Slitherlink with 20 clues taken out as dominoes and their original positions shaded. For more lucid rules please visit MellowMelon’s puzzle 263.

Domino set is all possible dominoes exactly once each: {00,01,02,03,11,12,13,22,23,33}

Twitter Bandwagon

Tue, 01 May 2012 11:58:32 +0800

Note: My 2012 self wrote this. It is preserved for historical interest and amusement.

Hahahahahahahahahahahahaha look at all the services

ahem

So, if you’ve been hiding under a rock for the last decade, Twitter is a platform for microblogging, i.e. blogging with very short posts, called tweets, which have to be under 140 characters after they shorten all the links for you for no reason, often after you’ve already shortened it once somehow-or-other. And yes, I hopped onto the bandwagon during procrastination. Everybody who matters on the technological edges of the internet seems to have one.

I’m not arrogant enough to imagine I could compare Twitter to anything else authoritatively… I only barely count myself as using it. But a brief set of first impressions should be okay. Twitter is very public: you can see everybody’s tweets, who everybody is following, and who everybody is being followed by; the single privacy setting is a simple binary choice to lock up your account, so that everybody who wants to see what you posted needs your explicit authorization.

My Facebook feed consists of entries such as:

photographs of people I barely recognize, which I scroll past quickly… unless my mom comes up and says “Who is that?” and spends ten minutes looking at more such photos while asking me questions like “How do you go to the next picture?” or “Why is this photo so blurry?”
context-less fragments of some larger conversation, e.g. “LOL!” or “linglinglinggg” (copied verbatim from a status)
alerts of J. Random Person having taken a Personality Test or scored too many lines in Tetris
Meta-Facebook infographics, like a cloud of your closest friends or number of status posts. I tend to… have an extraordinarily negative impression of the type of narcissistic achievement-reliant… people… who need rewards at every step, except that they seem to be everybody… *sigh

Coup de Grâce

Mon, 30 Apr 2012 19:22:49 +0800

Yes, it’s official now. I’m on the 2012 International Mathematical Olympiad team bound for Argentina, and if I didn’t make a post about this I would be ashamed to call myself a blogger. So, a little moment of smug self-satisfaction should be justified, I hope? And not to mention, last year’s title of youngest Taiwan contestant is not yet passed? Let’s cue the evil laughter!

…or maybe not.

Here is a simple tabulation of our selection problems:

GA/GN/CG/GNC/NGA
AG/CA/NG/GCN/AGA
GA/GN/CA/GCN/AGC

Algebra x9, Combinatorics x7, Geometry x12, Number Theory x8. In other words a distribution in perfect negative correlation with my estimated ability in each subject. At least, that’s how I’ve always estimated them before about a month ago. Ouch, the last stage was the only one of the three where problem distribution for combinatorics actually reached its fair share. (Alternative interpretation: 2011’s distribution was majorly f123ed up with only one real geometry problem, which just means that this year’s battle will probably be difficult for me. (Alternative alternative interpretation: the evil, nasty, wicked, depraved windmill was actually an outrageous negative for me. Gee, I don’t know how to feel. But I should actually do stuff instead of wildly speculating; let’s get back to the topic.))

Scheduled Blogging

Fri, 20 Apr 2012 11:43:31 +0800

Some bloggers have a regular schedule for posting and forcing themselves to meet the deadlines. In essence, something like “updates every Thursday.”

For me, I think this is a bad idea, because it forces me to write. If my day is boring and uneventful as it quite often is and I still have to crank out a post, it would not be a post that readers would enjoy. Better once-a-month enthusiastic, interesting posts then an ugly stream of tedious drudgery for the visitor to wade through every time, stuff like (quoting one random ancient post):

Puzzle 15 / Sudoku / Happy Birthday!

Sun, 25 Mar 2012 00:00:08 +0800

A bonus gift for the birthday of a very important person! Ignore the colors while solving.

Puzzle 14 / Slitherlink

Thu, 22 Mar 2012 20:46:51 +0800

Just a normal one this time.

Note-taking

Wed, 21 Mar 2012 18:43:09 +0800

Finally getting into geography honors. And surviving, somehow, with grades that still might count as ridiculous-in-a-good-way. The one big change I’m getting used to is the need to take actual hardcore notes.

For eight years, most classes I’ve gone to, both inside or outside school, have been straight from a book or handout, which would be so easily read and comprehended (…to me) that any notes would be a waste of energy. A couple science teachers would make us take notes and count them as a grade. All you had to do to get an A was write down most of the important bits, even if the chapter sections were written in exaggerated cursive that took up half the page and there were random teddy bears straddling the margins, as in my notes.

There was a stage in maybe seventh grade where I told myself I would make neat, doodle-free notes that actually summarized the stuff in biology (the easy seventh-grade kind (not that we still remember all of it)), and to get to that goal I would force myself to use only one page for each section, with a special way to mark the vocabulary words. It helped studying a little, but the stage didn’t last, and I ended up doodling again.

Even when the going finally got tough and understanding became a nontrivial task, I still had irrelevant embellishments and a bunch of artificial fonts for my “notes”. Even in the days when I was free to go to the Chiao-Tung University for classes twice a week (and still get consistently ridiculous grades, judging by the score breakdowns the prof gave us after every test), my notes looked like this.

Exhibit A: mathematical analysis/advanced calculus notes, circa 2010

Puzzle 13 / Akari

Mon, 19 Mar 2012 06:44:28 +0800

Somewhat depressing almost-symmetry.

Puzzle 12 / Sashigane

Tue, 13 Mar 2012 13:30:47 +0800

If you are reading this, then our APMO testing time is over! There’s a small chance of me being really happy or really frustrated about how I did, but I’m betting on a solid “meh.”

Rules page by mathgrant. There’s no way I’m going to memorize the Japanese name yet. [edit: It’s Sashigane. It’s not that hard.]

Puzzle 11 / Smullyanic Dynasty

Tue, 06 Mar 2012 18:25:47 +0800

Ruleset designed by Zotmeister.

Puzzle 10 / Nurikabe 3

Sat, 03 Mar 2012 18:00:11 +0800

A ratio-preserving enlargement of the janko.at sample invocation puzzle, perhaps. I wanted to try using smaller clues. Finally a grid too large for full-size displaying! Is that even supposed to be an achievement?

Puzzle 9 / Yajilin

Tue, 28 Feb 2012 12:00:09 +0800

Man, hacking new puzzle types into the image generator is an amazing way to procrastinate.

Puzzle 8 / Fillomino

Sun, 26 Feb 2012 12:00:58 +0800

Hey, a “theme” (look at the corners)! Honestly though I’m just spreading out my puzzle posts so there’s some illusion of regularity.

English Names

Sat, 25 Feb 2012 23:08:46 +0800

Note: I wrote this in 2012. Maybe it’s kind of amusing?

For some reason, everybody around here seems to think that adding English characters, no matter how broken or meaningless, confers an added sense of quality or superiority. I don’t really understand the mindset here but it’s the only explanation I can come up with. It’s certainly not to make the lives of our English-speaking population any easier.

We were sharing songs in Chinese class with literary techniques, and there were a bunch of songs, including mine, by this pretty famous singer with the stage name Fish Leong. Okay, it’s kind of cute and it’s a translated homophonic Cantonese pun, so it makes some sense, although I wonder what people would think the name meant if mentioned without any context. There was this more obscure guy a couple seasons back in the reality TV singing competition (see, no original shows around here) whose name was Quack. smacks head It’s also kind of cute if you only know that the word is the sound a duck makes, which probably holds for most of the audience. But still, it takes just five seconds to put it into Wikipedia. Oops?

Puzzle 7 / Slitherlink [All Twos]

Wed, 22 Feb 2012 18:47:04 +0800

It’s 2/22 and I have low standards. This is a normal Slitherlink, except all the 2s have been given to you. Thus, empty squares cannot have exactly two edges around them. Of course it’s been done before (guess who?) I appear to be drastically overshooting a monthly schedule :P

Puzzle 6 / Fillomino

Tue, 21 Feb 2012 17:55:52 +0800

Not actually my first try, but I guess I don’t need to resort to 6x6s to fill up my quota just yet, do I? Okay for the absolutely uninformed, this is a Fillomino (or see MellowMelon’s rule page). I’ve switched to 32x32 pixel cells because they seem a reasonable size and it’s possible to express all pixel sizes as an exact floating-point fraction of the cell side so my image generator can be used in a general way to get perfect stroke thicknesses without worrying about any rounding errors no matter how obviously numerically insignificant they would be in this case.

Technological Fails Continue

Wed, 15 Feb 2012 22:11:00 +0800

Note: My 2012 self wrote this. It is preserved for historical interest and amusement, and does not reflect my current beliefs or attitudes.

Hardware:

The laptop I’m typing this on is over two years old. This is not a lot by some measures, but weird spontaneous glitches are starting to accumulate to the point where they’re getting on my nerves. The internet card still needs an extra reset to start working half the time, and occasionally warrants a full reboot, which costs five minutes. The USB ports are loopy, some windows just show up black when they feel like it, and there’s a steadily climbing whir in the background. I’m kind of anticipating the moment the whole thing just drops dead.

Well, I’m not about to run out of computers to use (there’s a noisy XP desktop that also barely works despite handling all our print jobs, but also one spanking new eight-core CPU laptop, which Dad considered a valuable enough investment (?)) but such a loss is still not something to be dismissed lightly. And the externalized cost is far more important and chilling. Who knows how many kids in the Congo had to mine coltan, or how much conflict has occurred over the crude oil, or what awful conditions those sweatshop-assembly workers are going through? Annie Leonard’s words still resonate with me from when we were first shown the video a year ago. Which is more recent than this laptop, so that doesn’t mean that much. I think a couple months ago I would have absolutely no second thoughts about getting a new one, though. Yup, I’m in a quandary (ha ha vocabulary) on the balance between desensitization and compulsive hoarding of stuff.

Puzzle 5 (Liar Slitherlink)

Tue, 14 Feb 2012 12:19:00 +0800

One puzzle a month! What a prolific schedule! A Liar Slitherlink as created by MellowMelon (probably). Normal Slitherlink rules except exactly one clue in each row and column is false; you figure out which. But I bet you knew that already.

Bilingualism

Sun, 12 Feb 2012 22:11:00 +0800

So, as triggered by my confrontation with the Chinese book report (remember? whatever the answer is, it’s okay): a reflection on my incompetence at dealing with two languages, and why this matters, or not.

I can think in both languages. It’s a natural product of our school environment. The two languages often have to complement each other; most of the nerdy terms or globally relevant allusions are English-exclusive (I couldn’t talk coherently about SOPA in any language other than English!), but a lot of cultural and geographical staples around here are Chinese only. And sometimes there are unexpected holes where an innocuous-looking phrase simply has a few too many connotations to translate perfectly (the example I always get stuck on, and have yet to solve satisfactorily with anything short of a full sentence recasting, is “appreciate”.)

Adventures in Crappy Markup

Fri, 10 Feb 2012 21:39:00 +0800

There are two big elementary and middle school competitions around this part of the globe. Well, “big” according to “I’ve heard of it”, which is by no means an accurate measure of, well, anything. I don’t go out of my way to look for them any more, even though… hold on, am I still eligible? Whatever. But in any case, diverting any unnecessary energy from the olympiad-proof-training is probably not a good idea now.

Puzzle 4 / Nurikabe (+Lists of Obscure Stuff)

Wed, 11 Jan 2012 21:11:00 +0800

I was like “Let’s make a 15x15!” and got confused by the graph lines and stopped early. Anyway, I think the steps aren’t so trivial now. I’m still too lazy to fix my generator, however. yes, normal Nurikabe

Puzzle 3 / Nurikabe

Tue, 10 Jan 2012 17:00:00 +0800

I only just managed to make a 10x10 that’s not broken.

janko.at applet

Autological Procrastination

Thu, 05 Jan 2012 17:33:00 +0800

#ifdef BORING_SELF_DEPRECATION

So obviously this isn’t a good parody and the song is ancient (under some “pop” definition, which is probably not a very discriminative label), at over four years. Just randomness that finds its way onto my iPod. And the words are not very creative, and there are even two lines that survive unscathed because they fit reasonably and I can’t think of anything better (and I don’t even know if this is supposed to be bad, I just want to ensure nobody expects otherwise).

#endif

Whatever, this has been sitting in my draft box for at least one month.

Freedom Writers SEO (or lack thereof)

Tue, 03 Jan 2012 17:46:00 +0800

Note: My 2012 self wrote this. It is preserved for historical interest and amusement. Two months ago for some random reason I noticed that somebody had found this blog by Googling for the Freedom Writers contest page. Shortly thereafter, the school went ahead and held it for the second time, two years after the first contest, and even more people have started searching for some combination of “ibsh freedom writers”, resulting in an anomalously large number of hits to a certain just-over-two-years-old post.

Puzzle 2 / Slitherlink

Sun, 01 Jan 2012 00:01:00 +0800

Written for the new year of 2012. (janko.at applet)

Hello

Sun, 01 Jan 2012 00:00:00 +0800

A new year. A new start. And just a chance to abuse the phrase “See you next year!” It’s hard to get tired of using it once every 365.24 days.

So, I have decided to open up my other blog to people.

There are a few reasons for not doing so previously. Firstly, there’s a lot of silly writing with unexplained LOLs and exclamations all over the place in the archives, not to mention the countless other sorts of weirdness linked to the handle I’m using here that’s spread over the rest of the interwebz. But I like to keep old stuff as some kind of record that my past self existed, and I’ve given up being embarrassed about them. And anyway, now and then I’m still performing embarrassing acts that outstrips any of this stuff by miles.

When I was thirteen*, the world was a different place to me. I imagined thousands of creepy people staring at computer screens out there, waiting to kidnap children and sell them to clients halfway across the globe the instant they figured out their addresses and statuses as minors. I don’t blame that old me; there has been at least one computer class devoted to videos of this type.

2011 Summary

Sat, 31 Dec 2011 23:59:59 +0800

Note: This post is backdated. I am writing this post in 2019 because, as part of the Big 2017 Remigration, I have decided to delete most of the posts because they were too embarrassing and sparse on information, but figured I might keep a rundown of the highlights.

2011, on this blog:

Freedom Writers

Tue, 27 Dec 2011 08:48:00 +0800

Note: My 2011 self wrote this. It is preserved for historical interest and amusement, and does not reflect my current beliefs or attitudes. Also, it has linkrotted.

Alrighty, if you’re looking for the IBSH Freedom Writers contest website, its URL is http://freedomwriters.ibsh.co.cc/. (2013/03/28: The link is now dead. I’m not surprised; it’s just more evidence that free websites of the “do your own html files” type are really fragile things.) I just tried to help my sister find it through Google, it’s nowhere to be found, and instead there are hits in ancient archive posts from this blog.

Puzzle 1 (Wild Slitherlink Appeared!)

Mon, 28 Nov 2011 19:24:00 +0800

Fairy Tale

Tue, 27 Sep 2011 18:10:00 +0800

Note: My 2011 self wrote this. It is selectively preserved for historical interest and amusement from a lot of similar, chronologically nearby posts. I am not as angsty any more.

I don’t know where to start.

First there was a headache. No biggie, sleep it off. But it’s easy to lose yourself

The pain, the random gusts of nausea, confusion, irritation… it’s another person in this body, speaking a foreign language I can’t even begin to fathom

playing by his own rules, won’t let you figure them out. his kingdom, and there’s not even a way to surrender or take the path of least resistance. Every path looks the same from here

blackness, vagueness, shadows, defying all interpretations

Nerdy Writing

Mon, 05 Sep 2011 21:18:00 +0800

Note: My 2011 self wrote this. It is selectively preserved for historical interest and amusement. It’s just meta enough to be funny, I think. I can look at the posts I made in fourth grade, and understand how I might get exaggeratedly happy about these tiny things, and write this ramble that goes up and down and all over the place. Anyway apparently I wrote “to indulge in a colloquialism” less than a year ago in a school essay and now it sounds plain freaky to me.

Normality

Tue, 09 Aug 2011 19:51:00 +0800

Note: My 2011 self wrote this. It is selectively preserved for historical interest and amusement from a lot of similar, chronologically nearby posts. That’s all. I am not as angsty any more.

So. I was hoping I could blog for once without predictably explaining something about how this doesn’t mean anything about future posts or activity or anything, but apparently I can’t get started without a lame start like this.

Eight months have passed since I started my fight with leukemia. Yes it has been a rough eight months, full of unpredictable pain, nausea, diet restrictions, and freakishly-sized needles.

I’ve been waiting for I don’t know how long for everything to go back to “normal”, but now that I look back I can no longer imagine the idea. The world, outside, still seems to be rushing at its insane pace towards maximum chaos. Economic and natural crises still seem to be always around the corner. But in here, in the hospital ward, or at home, it’s a really different feeling. I feel completely disconnected. Nothing changes; every day is waiting, waiting, waiting for the future, for a better moment or feeling or achievement.

For what, really?

2010 Summary

Fri, 31 Dec 2010 23:59:59 +0800

Note: This post is backdated. I am writing this post in 2018 because, as part of the Big 2017 Remigration, I have decided to delete most of the posts because they were too embarrassing and sparse on information, but figured I might keep a rundown of the highlights.

2010, on this blog:

2009 Summary

Thu, 31 Dec 2009 23:59:59 +0800

2009, on this blog:

Technological Fails

Sun, 20 Dec 2009 18:05:00 +0800

Note: My 2009 self wrote this (except for the insertions by my 2013 self). It is preserved for historical interest and amusement, and does not reflect my current beliefs or attitudes.

Strange things:

More Random Blathering

Sun, 16 Aug 2009 21:47:00 +0800

Note: My 2009 self wrote this. It is preserved for historical interest and amusement only, and does not reflect my current beliefs or attitudes.

Somehow my cousin deleted the Eragon game from his PSP. Ah well, it was fun while it lasted. Current project: get that secretary-problem paper done. It looks much nicer now, due to the references and big bold titles.

New Goal: 10 Keepers

Sun, 16 Aug 2009 13:38:00 +0800

Note: My 2009 self wrote this. It is preserved for historical interest and amusement only, and does not reflect my current beliefs or attitudes.

Now and then I find myself lapsing into a bunch of 42-related questions. The most recent occurrence was the day before yesterday, and I decided that the meaning of life is to find your meaning of life. Since that would tautologically entail that I had already completed my meaning of life, I decided to reject it, even though it has a pretty nice ring to it. Some goals:

Back from Math-Camp Post...

Thu, 13 Aug 2009 19:23:00 +0800

Note: My 2009 self wrote this. It is preserved for historical interest and amusement, and as a testament to how far I’d go to typeset math equations in ASCII art.

I have just come back from a week of continuous mathematics, board gaming, and hitting people with sticks to ensure that they get up in time. Yippee! Those problems sure do get around.

Sample problem: This problem rocks!

Winter

Tue, 27 Jan 2009 20:09:00 +0800

Note: My 2009 self wrote this. It is preserved for historical interest and amusement only, and does not reflect my current beliefs or attitudes.

I’m reconsidering. It’s not that boring. LOLZ. There it goes again.

Particulars… well, I got to play my cousin’s PSP. It was an instant like the instant when I saw the Krusty Kreme shop during our visit to Indonesia (shoot, my mouth is watering again), I found a very interesting game logo. A shining blue lowercase E. Most people would think of the Internet Explorer logo. But obviously, Microsoft is probably not affiliated with Nintendo or whatever company made PSPs; even then you can’t play Internet Explorer.

2008 Summary

Wed, 31 Dec 2008 23:59:59 +0800

2008, on this blog:

Lost

Mon, 29 Dec 2008 20:09:00 +0800

Note: My 2008 self wrote this. It is selectively preserved for historical interest and amusement from a lot of similar, chronologically nearby posts. That’s all.

I have a life and I still don’t know what to do with it. I like making powerpoints, programming, typing tests, made-up hyperbolic IQ tests, Gmail, and odd things.

All that animation has gone to my nerves. And Bookworm Adventures pining. Best word so far: VORACIOUS, which earned me a blue gem tile, which froze somebody. I want to design games for PopCap too, because then I get to play the ones they already have for free.

Lolcode:

Eternity Bus Ride

Sun, 14 Dec 2008 08:46:00 +0800

Yesterday I got to sit and vegetate on a bus for a total of four hours. My MP4 was already getting boring. In fact the time spent at the math lesson was less than that. Luckily the bus home had a TV that kind of worked, and showed a replay of the show that self-translates as “One Million Star”. I only watched a bit. The rest was highly tumultuous slumber. Dinner was spaghetti, which helped.

A () of a Lot of ()

Fri, 12 Dec 2008 21:41:00 +0800

Note: My 2008 self wrote this. It is preserved for historical interest and amusement.

Arvorie has just spammed my email account with three emails, two of them talking about palindromes.

“What? The fat in your head?”

My latest hard cryptogram, used with a substitution cipher:

Change

Tue, 21 Oct 2008 20:38:00 +0800

I like this life.

I remember somewhere in some book (Walk Two Moons, I think) someone said sometime something about everybody being afraid of change. Change’s only problem is that it is completely unpredictable.

The Return of the Omnipotent Biker

Sun, 19 Oct 2008 20:46:00 +0800

Note: My 2008 self wrote this. It is selectively preserved for historical interest and amusement from a lot of similar, chronologically nearby posts. That’s all.

Biking is fun. Unfortunately it doesn’t require as much exertion as other workout methods do. The thing you learn most from it is how to obey traffic.

“I asked him if he knew what the word ‘obey’ meant. He replied,”Sure. It’s a place online where you can buy stuff.”“

Spanish, Music, and Doing the Wrong Thing

Thu, 16 Oct 2008 18:15:00 +0800

Note: My 2008 self wrote this. It is preserved for historical interest and amusement, and is not representative of my current beliefs or attitudes.

Yesterday I got persuaded by my mom to seriously use the LearnToSpeak Spanish CD we bought. I say “Hasta luego” into the mic and it says I selected “Estoy bien”. Still, the vocabulary it selects are far better than the ones I selected haphazardly. ¿Qué quiere decir “…”? Well, I’m stopping the finding of new vocabulary in Spanish madly.

Today I lost my Kitchen Midden rubric by clipping it into the questionnaires. I wasn’t sure until I found it there. I flipped through the questionnaires and found it in ten seconds. Wooooo! WHAT ARE THE ODDS? Luck.

Cold

Mon, 13 Oct 2008 17:17:00 +0800

Note: My 2008 self wrote this. It is selectively preserved for historical interest and amusement from a lot of similar, chronologically nearby posts. That’s all.

Hooray! Something I ate today cured my cold! Well, they assuaged it for today at least. Perhaps by dinner I’ll be coughing like a donkey with terminal asthma again.

Okay, enough with horrible similes. Luckily or not, in P.E. class we didn’t do the lethal 100m dash timing. Instead we practiced jumping. Hooray! It’s not as exerting.

Sicknesses and Sundays

Sun, 12 Oct 2008 11:23:00 +0800

Note: My 2008 self wrote this. It is selectively preserved for historical interest and amusement from a lot of similar, chronologically nearby posts. That’s all.

Today is Sunday. Tomorrow is when I go back to school. *sigh*

Pearl Milk Tea Again

Sat, 11 Oct 2008 19:43:00 +0800

After submitting my article onto my Magnum Opuses website section I got to drink some more pearl milk tea that wasn’t sweet at all.

When I was little I used to look at everybody drinking bitter things like tea, coffee, beer, wine, and all that. I simply couldn’t imagine growing up and liking them. Everything good at that time was sweet, sugary, sweet, and unhealthy. Then I realized that I hated candy.

Ah, whatever.

Physical

Sun, 05 Oct 2008 20:44:00 +0800

Recent excercise: I’ve bicycled all over the place, almost going into Jhubei. Obviously, with parental notice. In fact they rode with me. Or, more strictly speaking I rode with them. Whatever. Also I’ve done a few pushups wrongly. And I’m typing, I guess. Ah, whatever.

Virtues, Complaints, and Trash

Thu, 02 Oct 2008 18:48:00 +0800

Note: My 2008 self wrote this. It is selectively preserved for historical interest and amusement from a lot of similar, chronologically nearby posts. It is not representative of my current beliefs or attitudes. I hope you enjoy the glimpse into a sixth grader’s psyche while he attempts to wax philosophical.

I have been pondering an interesting problem for a long time. Which virtue is the best, the most important, the most worthy of epitomizing the word “virtue”? Due to homework constraints I have been unable to put this up for a long time, which is frustrating.

My candidates: First, honesty. Then we have kindness. Then responsibility, and optimism, and courage, and intelligence. It doesn’t look like a fair match, really.

Human Dependencies and More Trash

Tue, 30 Sep 2008 16:41:00 +0800

Humans depend on electricity. It’s the main problem with blackouts.

Prehistoric people didn’t have this dependency. If our world is further electronized, blackouts will be very dangerous and will have to be made more robust.

NeoBanner

Mon, 29 Sep 2008 18:42:00 +0800

Note: My 2008 self wrote this. It is selectively preserved for historical interest and amusement from a lot of similar, chronologically nearby posts. That’s all.

Hooray! I got a new banner! Is there something rebellious lurking just beyond my grasp?

Peanut Butter Viscosity

Mon, 29 Sep 2008 08:44:00 +0800

Note: My 2008 self wrote this. It is selectively preserved for historical interest and amusement from a lot of similar, chronologically nearby posts. That’s all.

Note to self: PB gets stickier when toasted. Slightly strange because under heat it should flow easier, but it’s probably the same principle as the way cement works.

Yay! I'm back!

Mon, 25 Feb 2008 18:33:00 +0800

Note: My 2008 self wrote this. It is preserved for historical interest as a glimpse into the history of this blog.

Blog revival!!! Thanks to Jonathan for reminding me of the existence of Blogger.

Today was a good day all in all.

Accomplishments:

2006 Summary

Sun, 31 Dec 2006 23:59:59 +0800

2006, on this blog:

Your Typical Friday

Fri, 08 Sep 2006 19:15:00 +0800

Note: My 2006 self wrote this. It is preserved for historical interest (as the first post ever made on this blog) and amusement, and is not representative of my current beliefs or attitudes.

Today was an… ordinary special day. Well, an ordinary day from all aspects, but a special day if you count the way everybody got hyperactive after lunch.

Well, duh!

Just your typical Friday. Typical Fridays, we get computer class. And I can repeat it again.

Color

Mon, 01 Jan 0001 00:00:00 +0000

Bruce Lindbloom has a ton of equations, but I just want the big ones on one page. We’ll assume sRGB, which implies using D65 as white (if you’re using Bruce Lindbloom’s calculator to check your implementation, make sure to set these).

RGB ↔︎ Linear RGB

Let $\Xi$ (one of $R$, $G$, and $B$) be an RGB component in the range $[0, 1]$. (This is an obnoxious variable choice, but I’m trying to not overload any variable names in this entire post.) If you have RGB values in $[0, 255]$, divide them by 255. It can be converted to/from the linearized component $\xi$ (one of $r$, $g$, and $b$) as:

\[\xi = \begin{cases} \Xi/12.92 & \text{if }\Xi \leq 0.04045 \\ ((\Xi + 0.055)/1.055)^{2.4} & \text{if }\Xi > 0.04045 \end{cases}\]

\[\Xi = \begin{cases} 12.92\xi & \text{if }\xi \leq 0.0031308 \\ 1.055v^{1/2.4} - 0.055 & \text{if }\xi > 0.0031308 \end{cases}\]

This is called “companding”.

However, you can use $\xi = \Xi^{2.4}$ and $\Xi = \xi^{1/2.4}$ in a pinch.

Linear RGB ↔︎ XYZ

Convert between XYZ and linearized RGB. Again, this assumes sRGB and D65.

\[\begin{align*} X &= 0.4124564r + 0.3575761g + 0.1804375b \\ Y &= 0.2126729r + 0.7151522g + 0.0721750b \\ Z &= 0.0193339r + 0.1191920g + 0.9503041b \end{align*}\]

Coq Reference

Mon, 01 Jan 0001 00:00:00 +0000

It seems like a rite of passage to create one of these because there are so many Coq tactic cheat sheets out there and there’s just so much to learn. Here’s mine.

This is mostly about tactics but I realized not really.

Links:

Coq Tactics. Authoritative but dense.
Logical Foundations (Software Foundations Volume 1). I think the order of ideas makes pedagogical sense but also makes it hard for me to look up particular tactics or concepts.
Other Coq cheat sheets found by Googling “Coq cheat sheets”:
- Coq Tactics Index (Joseph Redmon)
- Coq Tactics Cheatsheet (Cornell CS3110)
- Coq Tactics Quick Reference (Adam Chlipala) / the Formal Reasoning About Programs book also has a nice appendix
- Coq Tactics (UPenn ???)

Meta-notes: I cover a lot of weak tactics because I like knowing exactly what my tools are doing. I try to use the variants of tactics that explicitly name things produced when possible. I am sure there is nomenclature I don’t understand precisely and use sloppily in this list; I am also sloppy with metavariables. Even things that are correct might be horrible style. There are likely other errors and omissions. They might be fixed one day. I’m putting this up nevertheless because it’s personally useful.

Things I wish I knew but didn’t learn from Software Foundations or Coq tactic cheat sheets

The first two sections are not about tactics per se but how to find theorems to use and how to use them. Knowing how to use all of these query commands is super useful.
To clean up repeating subexpressions with “local variables”, I find remember expr as X eqn:Hname. easier to work with than set (X := expr).
pose proof expr as Hname. adds expr to the context, with name Hname. Modus ponens where you know H1 and H2, which is “H1 implies H3”, is just pose proof (H2 H1) as H3.
Software Foundations covers bullets and curly braces early, but I like subgoal specification with 1:, 2: etc., which can really help limit nesting depth. 2: (tactic that solves subgoal 2). If you want more bullets, there are infinitely many, not just three. After - + * you can use -- ++ ** --- etc.

diagrams Reference

Mon, 01 Jan 0001 00:00:00 +0000

diagrams is a nifty Haskell library for making vector diagrams. I keep coming back to it to generate graphics for puzzles:

the very old A Signature Puzzle from this blog
A Fork in the Road (DP Puzzle Hunt)
Symbols (Galactic Puzzle Hunt 2020)
A Lot of Research into Things That Have Very Little Meaning (Silph Puzzle Hunt)

I got sick of relearning it every time, and I think there’s some small chance other people will find it useful too, so I wrote something up. This post is a sort of reference that tries to compromise between the quick start tutorial and manual on one hand, and the API reference on the other, to try to be deeper and more comprehensive than the former, but also flow better and be easier to navigate than the latter. Some types are just really intimidating when fully written out…

circle :: (TrailLike t, V t ~ V2, N t ~ n, Transformable t) => n -> t

To avoid unhelpfully generic types, I will deal concretely with two-dimensional diagrams that measure everything in Double, and will frequently abbreviate complex types with an asterisk, like I will write V2* for V2 Double. I will introduce these aliases along the way for easy greppability. They’re not legal Haskell, of course.

This reference assumes basic-to-intermediate Haskell knowledge. Some of the more intermediate stuff includes:

Monoids, and that the Haskell Monoid operator is <>
Typeclasses. I will sometimes write fake type signatures as abbreviations for typeclass restrictions: for example, TrailLike is a typeclass, and I might say or write that a function returns TrailLike when I really mean TrailLike t => t, any type t that is in that typeclass.

van Laarhoven lenses may help, but mostly I’ll try to black-box them.

Factorize

Mon, 01 Jan 0001 00:00:00 +0000

A basic JavaScript factorizer. Warning: it uses extremely dumb trial division, so numbers with large prime factors will quite likely hang your browser, and big numbers will overflow or lose precision. If you want to factor the big fish, use Alpertron’s ECM applet or something. factor! append? fancy?

Haskell Stash

Mon, 01 Jan 0001 00:00:00 +0000

Editor’s note: This is almost certainly years out of date. cabal has v2 commands and stuff now? Sorry.

init

Mon, 01 Jan 0001 00:00:00 +0000

1

Firefox
- LeechBlock, Xmarks, HTTPS Everywhere, uBlock Origin
- Formerly: Pentadactyl (nightlies), LastPass, Disconnect, All-in-One Sidebar
Dropbox (db.tt)
(g)Vim / MacVim
- NeoBundle; jellybeans, syntastic, airline, fugitive, unite.vim, nerdtree, …
- Make sure you change your home folder and other paths in your .vimrc if necessary.
LaTeX
VLC
Anki
Geogebra, CaRMetal
osu!
Gargoyle
MuseScore
μTorrent
VeraCrypt
Gyazo

Iverson Bracket

Mon, 01 Jan 0001 00:00:00 +0000

Very simple to explain: if $P$ is a statement, $[P]$ is 1 if $P$ is true and 0 if not. So for example \[\begin{aligned} \lbrack 1 < 2\rbrack &= 1 \\ \lbrack 1 > 2\rbrack &= 0 \end{aligned}\] It’s like using a boolean as an integer in C or Python. It’s useful to keep yourself organized when you’re writing summations, especially if you’re summing across terms with a weird condition or if you need to exchange two sums.

Java Clipboards and Data Transfer

Mon, 01 Jan 0001 00:00:00 +0000

(Ported from betaveros.stash. Wow, I get syntax highlighting and footnotes! Probably years out of date though. I probably wrote this somewhere in 2012–2014, but am editing this parenthetical in 2021.)

A quick brief guide. At least, that’s how I planned it.

A lot of stuff is in the package java.awt.datatransfer. Class Toolkit is in java.awt.

Some basic classes. The class Clipboard is a clipboard, obviously. Its content is/will be an instance of the class Transferable. Some content can be read as different types of objects depending on what you want; to choose which type you use an instance of DataFlavor. It provides three basic ones: DataFlavor.imageFlavor, DataFlavor.javaFileListFlavor, and DataFlavor.stringFlavor.

Okay, now step by step. This is the low-level method.

Get the default clipboard with Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
Get a transferable with Transferable content = clipboard.getContents(null); ¹
Check if content can be read as the kind of object you want with (content != null) && content.isDataFlavorSupported(someFlavor)
If it does, get the object with content.getTransferData(someFlavor) ².

If you just want a quick-and-dirty function:

static String getClipboard()
        throws java.awt.datatransfer.UnsupportedFlavorException, IOException {
    return (String) java.awt.Toolkit.getDefaultToolkit()
        .getSystemClipboard()
        .getData(java.awt.datatransfer.DataFlavor.stringFlavor);
}

Linear Algebra

Mon, 01 Jan 0001 00:00:00 +0000

This is a matrix. \[\begin{bmatrix} 1 & 2 & 3 \\\\ 4 & 5 & 6 \end{bmatrix}\] It has 2 rows and 3 columns, so it is a $2 \times 3$ matrix. Matrix addition and multiplication-by-a-scalar is done componentwise. Matrix multiplication is done trickily; it’s associative, distributive, commutative with scalars, linear, anticommutative-under-transposition. Vectors are like columns of matrices, or matrices with one column. Except row vectors are rows of matrices.

Operation Exchange

Mon, 01 Jan 0001 00:00:00 +0000

Limit + Limit

Cheaply, using an Iverson bracket expression:

\[ \begin{aligned} \lim_{a \to \infty} \lim_{b \to \infty} [a > b] &= 0 \\ \lim_{b \to \infty} \lim_{a \to \infty} [a > b] &= 1 \end{aligned} \]

For more continuity, use $\frac{a}{a + b}$ instead (Rudin Example 7.2).

Uniform convergence on one limit suffices to allow this exchange, almost by definition.

Limit + Continuity

Let

\[ f_\epsilon(x) = \begin{cases} 0 & \text{if } |x| \geq \epsilon \\ 1 - \left|\frac{x}{\epsilon}\right| &\text{if } |x| < \epsilon \end{cases}. \]

Paper Size

Mon, 01 Jan 0001 00:00:00 +0000

1in = 2.54cm

A4	= 21.0cm × 29.7cm	= 8.27in × 11.69in
A4 − 1in margins	= 15.92cm × 24.62cm	= 6.27in × 9.69in
Letter	= 21.59cm × 27.94cm	= 8.5in × 11in

Poker Formatter

Mon, 01 Jan 0001 00:00:00 +0000

Format poker cards for forum games and whatever without reaching for Unicode input methods.

The regex employed is essentially /\b([A2-9TJQK]|10)([CDHS])\b/g. You have to type in uppercase (otherwise even “as” would be filtered).

Problem Reference

Mon, 01 Jan 0001 00:00:00 +0000

(ported from wiki) Certain notable problems that I don’t want to look through a zillion pages to find. Iran TST 1996, notoriously reposted at least 35 times on AoPS (okay, many of these are actually modifications): If $x, y, z > 0$ then \[(xy+yz+zx)\left(\frac{1}{(x+y)^2} + \frac{1}{(y+z)^2} + \frac{1}{(z+x)^2}\right) \geq \frac{9}{4}\] ISL 1988 #4: if $1, 2, \ldots, n^2$ are placed in a $n \times n$ chessboard, some two adjacent numbers differ by at least $n$

Rudin Crib Notes

Mon, 01 Jan 0001 00:00:00 +0000

Brevity has been chosen over accuracy because the whole point is that you should know this stuff already.

Chapter 2: Basic Topology (+ some Ch. 3)

An isolated point of E is in E but not a limit point of it. E is perfect if it is exactly equal to its set of limit points. Equivalently, it is closed and has no isolated points. Ex. 2.44: The Cantor set is perfect.

A compact set is a set for which every open cover has a finite subcover.

Compactness or compact sets have these properties (with made-up names):

Stash

Mon, 01 Jan 0001 00:00:00 +0000

rustc -C prefer-dynamic

.meter-text { white-space: pre-wrap; }

launchctl stop com.apple.pboard
launchctl start com.apple.pboard

# requires ImageMagick
function img() {
    identify -format '<img src="%f" width="%w" height="%h" />' $1
}