Tuesday, June 26, 2012

Ocarina of Time

I completed the new Any% route (Ganon as child) for the first time today! My time was 48:15. I got the wrong warp on my second try (where the first was too early, so it didn't cost much), but then failed at Ganon's castle for a while. Also my bottle sucked a lot. The Ganon fight is tricky because you do the infinite sword glitch with the deku stick, but sometimes you have ISG on but it doesn't look like it until you actually walk around, so I think I got ISG a bunch of times and didn't realize it.

Since most of you probably don't know what I'm talking about, there was a major glitch found a couple months ago now, where you can warp from the Deku Tree (first dungeon of the game) to the Ganon castle escape (after the Ganondorf fight), then kill Ganon as child link. For reference watch this video: http://www.youtube.com/watch?feature=iv&annotation_id=annotation_124494&v=PaUCFrW_mEE&src_vid=JbceRzEL3ks

Also go check out speedrunslive.com!

Tuesday, September 13, 2011

A cute problem

Does there exist an algebraically closed field that is isomorphic to a proper subfield of itself?

Sunday, December 26, 2010

The Best Chinese Food I've Had

Comes from a restaurant called Grace Garden in Odenton, MD. I went there with family this Friday and had a great meal :). Of course, as with most Chinese restaurants, you have to go in a big group so you get lots of really good dishes.

Fish Noodles! How do they make fish into noodles? I really want to know.

Golden Shrimp. My cousin took two before I could get the picture :(

Crispy Eggplant: probably one of my favorite dishes that they have

Sichuan Triple Treasure: It's beef tongue, tripe, and intestines I think.

Braised Pork Belly: Always good

Pocket Tofu: It's so soft and has a really good flavor.

Some sort of green vegetable. Someone else can probably actually identify it.

Merry Day-After-Christmas!

Monday, December 6, 2010


lead to decisions. And decisions are hard.

Wednesday, November 24, 2010

Too Hard

Whoops, Tim already wrote a blog post with this same name. I'm using it anyway.

I was the problem czar for the Harvard-MIT November Tournament, which happened on Sunday, November 7, 2010. As problem czar, I was responsible for making sure that enough problems got written on time for the contest to run. That in itself was a huge task, made no easier by the relatively small amount of help that the February problem czars gave me. I personally wrote the majority of the test, with help from Travis in some key areas (he wrote many of the geometry problems), and from Jacob in not as key areas (he kept giving me problems about Bayesian inference...).

66 problems later, I get the (somewhat delayed) response from testsolvers: "Too Hard."

What is too hard?

Honestly I am probably too biased to comment, but I don't believe that it's possible for something to be too hard on its own. Being too hard can cause other issues, such as a lack of distinguishing power, but being too easy can also cause that. And I am fully aware of the issues that come from a test that lacks distinguishing power.

So when I see a complaint that something is too hard, what do I think? I feel that it is extremely more likely that some aspect of the undertaker is off rather than that the task is actually too hard. And it seems like others are the opposite -- they would much rather blame the test than the test takers, especially when they are the test taker.

Actually, I do that too. Lots of my blog posts last year were about things that I disagreed with in tests. Was it really the tests that were at fault or was it me? I think it was some of both. I don't think it's deniable that the HMMT calculus test was unable to distinguish between the top 4 competitors (hint: they tied), but at the same time it wasn't like the test gave them absolutely zero opportunity to distinguish themselves (the tie was at 28, not 50).

Regardless, I feel like there is this idea that if lots of people get two or fewer problems then the test is too hard. So, people say, make there be a few problems that everyone will get. But why? Now I've reduced my contest from 10 problems to 7. That doesn't seem useful at all.

I've rarely seen someone look at a test and say ``This is too easy,'' but many people will look at a test and say ``This is too hard.''

Monday, October 11, 2010

Linux iwlagn problems

This isn't really a content-full post, but if any of you are trying to install linux on a new computer and are finding that your internet connection drops after a couple minutes and a bit of traffic, it was a really annoying problem for me that existed for essentially the entire life I've had this computer. I only found the solution a couple days ago.

Right now, the iwlagn driver does not have full support for 802.11n. In fact, having 802.11n enabled will oftentimes screw up your internet connection in a very strange way. You retain your IP address, everything says you're still connected, but no transmission is really happening. You might notice a drop in bitrate from the output of iwconfig, but setting it to be higher again doesn't fix the issue. The issue is 802.11n.

The fix is to initiate the module with the option 11n_disable=1 or 11n_disable50=1. I had to use the latter. I am not sure, but I think it depends on which version of the driver you have (iwl4965 vs iwl5000). So make sure that you are compiling the driver as a module (do not build it into the kernel) and the fix is below.

If you have already booted and want to fix the issue, run the following commands as root

rmmod iwlagn
modprobe iwlagn 11n_disable=1
(or modprobe iwlagn 11n_disable50=1)

If you want the module to be loaded properly on boot, edit the file /etc/modprobe.conf (on gentoo; on other distributions this file might be somewhere else) and append the following line:

options iwlagn 11n_disable=1
(or options iwlagn 11n_disable50=1)

You might also have to use both options. I had to use 11n_disable50 and not 11n_disable. Regardless, one of these two should work and leave you with a perfectly reliable wireless card (without n mode, though).

Hopefully I helped someone with this post! This is a really really difficult bug to google.

Tuesday, October 5, 2010

Contest Theory

The IOI this year took a radically different approach to contest programming than the IOIs in the past. The Canadian Host Scientific Committee decided that it would be a good idea for the IOI to less favor the teams who have individuals who train very hard on standard algorithmic and data structure problems. I will put off judging whether that was a good or a bad decision until later in this post.

There is one fundamental aspect of writing a contest which is up for major contention and I don't believe that people pay enough attention to it. This is the question that you have to answer before you write a single problem for your test. That question is who should win.

Who should win? It seems like a simple question. The person who is best at math should win a math contest, the person who is best at skiing should win an Olympic medal for skiing. But these answers don't really tell you who should win. If I were to run a contest and I said that the winner would be the person who is best at life, nobody would take me seriously. Why? Because there are a relatively small number of things that would be on this contest. We wouldn't be able to determine the best sports player by just playing football, or just football and soccer, or any other (proper) subset of the sports in the world. And even if we were to play every sport in the world, I'd have to give an arbitrary weighting to each one. How do I compare two people if they have different strengths? It's simply not possible.

This problem arises at a lower level too. Let's look at football. Who is the best football player? I could say let's have a competition where everyone plays football. But this won't work. Maybe one player is a very strong quarterback and another is a very strong wide receiver, but only one of them gets their favored role. Well okay, let's have them pick their positions. We still have an issue. How are we supposed to compare someone's performance as a quarterback to another person's performance as a wide receiver?

Perhaps the answer is to have a quarterback competition, solely to determine who is the best quarterback. That is certainly a possible solution, but sometimes this will make the field too small. Say we object to a spelling competition because there are words from a plethora of sources, which some people will be better at than others. So we use our technique and say okay, we will have a spelling competition consisting of only English words of Sanskrit origin. How many people are specialists of such words? There are probably a few, but not enough to make a competition.

So we need some sort of compromise. We have to accept the fact that there are different specialties within whatever activity for which we hold a competition and that these are in some ways not comparable, but at the same time compare them somehow and determine a winner. It is for this reason that it is not the job of the contest to determine the best, but rather it is the job of the contest to determine the winner.

Of course, if there is a single best competitor, that person should win the competition. If one person is better than everyone else at every position in a football team, he would win a football competition. If your method of determining the winner didn't do that, then you have some problems. But this can be resolved by essentially any performance based scheme that uses positive weights on every event.

But in practically every case, there isn't a single dominating competitor, but rather several top competitors who all do well in different areas. So which one of them should win? It's up to the contest organizers to decide.

And this decision is often very debatable. Perhaps the most prominent example for me personally is the US IMO team selection. There is little argument to be made against the choice to favor those who will bring home the highest IMO scores. The argument stems from the fact that the US team leadership has seemingly decided that the most important subjects to be good at are algebra and geometry, casting aside combinatorics and, to a lesser extent, number theory. It's painful to look at the TST to see three geometry problems, graded in difficulty, so that it is almost certain that geometry skill will matter in team selection, in stark contrast with the single combinatorics problem, difficult enough that only Evan solved it (although I like to think I might have if I hadn't spent nearly all of my time on a geometry problem), clearly not mattering for team selection. The IMO claims to be a contest about all four main subject areas, but the US strategy says loud and clear that this is not the case.

Who is at fault? It's difficult to say. Maybe no one. Maybe everyone. It could be that the lack of combinatorics problems did not stem from a belief that combinatorics does not correlate to IMO score. It could be simply that there was not a sufficient supply of appropriate and interesting problems last year, so the TST was forced to be mostly comprised of the other subjects. But I'm not convinced that this was the case.

So now we return to IOI. The Canadians looked at the IOI and decided that they did not like the choice of winner that was made in the past. They didn't want someone who simply coded problems from online judges for the past year to have an easy road to victory. They wanted someone who could think about a problem which didn't have a standard complete answer and could still perform well.

So they changed the contest.

Gennady still won, of course. IOI might be a case where a dominating force actually exists. Regardless, the IOI change hurt my personal placement, but I can understand where it came from. The Canadians did well to explicate their goals, their means to reach those goals, and why those were their goals in the first place. I agree that the IOI had been reaching a less optimal position by simply escalating the difficulty of algorithmic problems, but I also think that the Canadians went too far in the other direction.

Next time you're involved in running a competition. Ask your group the question, ``Who do we want to win?''