Thursday, July 14, 2005

The Concept of Zugzwang

Zugzwang, best translates from German as “compel to move”. Normally, being able to move is a good thing, for it comes along with choice - to defend, to attack, to do whatever you want; however, at times, it can be quite disastrous! In Zugzwang, all choices are bad moves, so the player would rather not play a move at all (null move). In other words, all paths lead out of Rome. Zugzwang typically occurs in the endgame when there are a few pieces left on the board.

Chess engines often deploy a “null move” heuristic, which essentially is based on the assumption that in a reasonable position, a move is better than a “no move”. It effectively allows the computer to consider one less ply. While the null move itself is illegal, the position after it must be legal with the opponent’s turn, i.e the king cannot be left in check. In order to avoid a null loop, a chess engine does not consider a null move if the previous move in the search was also a null move. Usually, chess engines also filter out positions with a low number of pieces to avoid Zugzwang.

Players often think along those lines to gain perspective from the opponent’s side of the board - “What is my opponent thinking? What is he trying to do?” The null move heuristic does not work in every game. For example, in checkers, any reasonably advantage is usually gained because of Zugzwang.

Posted by Oleg Ivrii, 06:47 PM / Comments (1)

Tuesday, July 12, 2005

Ice Breaker (2nd edition)

Well, it has been a long time since I broke one of my bests… this isn’t a historic day or anything - they say, play enough, and you’ll do it eventually. But the thing is: the higher your best is, the harder it is to break it. Playing enough games won’t get you a 4000 rating (billions of games were played, but no one did it - human or machine in any category).

This time; however, the game isn’t just chess or kriegspiel… its crazyhouse! Most of you know the bughouse game (doubles chess) where you pass the captured pieces to your partner… well this is just doubles but on one board (whatever you capture is yours). While the two games are similar, the tactics can be very different, caution you! While good bughouse tend to be good crazyhouse players and vica versa, the correlation isn’t incredibly high.

Like kriegspiel, it is much more comfortable to play on a computer (hard inverting piece colours “by hand”, besides it requires 2 almost-full sets). I am also approaching 1000 tourney wins (not quite there yet). As they say, Progress must progress.

Update: Not approaching 1000 tourneys anymore. Been there and moved on, :). This also happened to coincide with my 900 tourney forfeit: did good work early, and had points to spare.

Update 2: When your rating is at your best, it is easy to break again. Thats exactly what happened. Now the best is 2151 instead of 2134.

Posted by Oleg Ivrii, 08:58 PM /

Saturday, March 12, 2005

Ice Breaker

When your ratings are high, breaking bests isn’t easy. Well, guess what? Today is my lucky day, I broke my first best in 2005. Anyways, the game is losers - very simple rules: if you can take, you have to take, and your goal is to lose all your pieces (except your king which technically isn’t a piece). Not only I broke my losers best, but I also broke the 2200 margin, which according to today’s standards is like huge. This puts me 1st on the “best losers” list (it shows the top 22 active players). To make matters even better, I have won my 900th tourney, which makes me 11th on the Tomato Winlist. This of course, makes me very happy. Now, I can sit back, relax and do homework.

Posted by Oleg Ivrii, 10:47 AM / Comments (1)

Monday, December 27, 2004

Are Coincide

I and [opponent] are playing a game. Both of us are there just to qualify. I offer draw, opponent accepts draw. This is where the fun begins.

I say: I don’t care       Reply: I don’t care

I say: I just want to qual       Reply: I just want to qual

I say: lol       Reply: lol

I say: we said the same thing       Reply: we said the same thing

I say: four times too       Reply: four times too

I say: five times, actually       Reply: six times, actually

Funny, how people from completely different places think the same. The guy is Australian, by the way.

Posted by Oleg Ivrii, 02:44 PM / Comments (2)

Sunday, December 26, 2004

Kriegspiel Championships

I played the ICC Kriegspiel championships today - both the 1 0 (1 minute per player) and 3 0 (3 minutes per player) divisions. In 1 0, I attained 6th place with 5/9 - Quad Elimination; and in 3 0 - second place with 7/10 - Triple Elimination. To participate in such events, one needs to do “well” in the qualifier tournaments which were held last week. Players which qualify but are not logged in at the start of the event must forfeited. Our good manager forgot to do this, so we started, had to abort (the absentees were paired just as well) and start over again. The guy who got 1st place - won both tournaments - and is also from Toronto, Canada. Well done.

Posted by Oleg Ivrii, 08:01 PM /

Friday, December 24, 2004

Look beyond the fog!

Its not chess, its kriegspiel! In this chess variant, you don’t see your opponent’s pieces. You can only see your own pieces, and have to guess where your opponent’s pieces are. When you try to make a move, if its illegal, you should make another move instead. To monitor both sides, a referee is required. He or she makes the following announcements when appropriate:

  1. Pawn at [square] captured
  2. Piece at [square] captured
  3. Rank check
  4. File Check
  5. Long-diagonal check
  6. Short-diagonal check
  7. Knight check
  8. [number] of pawn tries

Like Stratego, it is a game of incomplete information. Even mating with a king and a rook isn’t as trivial as it seems. Games with complete information or no information at all have been well analyzed, but the theory for games with partial information has yet to be developed. A truly complicated and charming game.

Posted by Oleg Ivrii, 01:56 AM / Comments (2)

Thursday, December 16, 2004

Inflated Ratings

Last year, I wrote my ISU for Data Management on the "Statistical Analysis of Internet Chess" [SAIC]. I studied the correlation between the duration, the number of moves and rating deviation. Here is the bulk of my research:

The classic etime (expected length of the game) is measured by the formula etime = time + (2/3)*inc. This formula comes from standard (long) games which last for 40 moves (on average). Under the official rating system (16 + D/25), the standard deviation is around 350.

It was decided that blitz games should be rated the same way. This may be convenient, but from a statistical viewpoint, it is a disaster. This is because blitz games are 60 moves long (on average) and hence the classic etime formula does not apply. This results in a greater standard deviation - around 425. That means the ratings are more spread out: standard chess ratings are capped by 2800 - but blitz ratings go well above 3300.

So what if the ratings are inflated? In a perfect rating system, it is expected that when two players play a sufficiently long series of games, their ratings will be approximate their 'true strengths' (relative to the other players). Hence, rating is meant to be a fair game. But in blitz, there is no such balance. That means that some players are more profitable to play then others.

Posted by Oleg Ivrii, 04:29 PM /

Thursday, December 9, 2004

You serve. I deserve.

I played some excellent chess the other day. But my rating didn't show much improvement. As a matter of fact, it suffered a little. The people don't even know how to play chess (actually it was losers) and still manage to beat me once in while. Well, I don't like that. I am supposed to beat them everytime. You serve. I deserve.

The rating system works in the following way. If you win against a player of equal rating, you gain 16 points and if you lose, well you lose 16 points. Of course, ratings are seldom equal, so there is a little adjustment. If the rating difference is d = opponent rating - your rating, you gain d / 25 points (could be negative). If the rating difference is really high, it is treated as 350.

So if a strong player plays a very weak player, he would gain +2 if he wins, -14 in case of a draw, and -30 if he loses. We shall denote it with (+2 -30) notation. This means he must win 7 in order to draw 1 (to break even).

Now suppose you are in a tournament and you are the only strong player (2150) and the rest are pretty weak (1900 avg). Even if its (+6 -26), you must win 5 games to afford to lose 1. And then you still only gained like what? 4 points?

But wait, it gets worse. After +6+6+6+6, my rating improved, and then it became (+5 -27), so +5-27 (I lost last round). This means I only gained 2 points. Bummer.

Posted by Oleg Ivrii, 10:16 AM / Comments (2)

Tuesday, December 7, 2004

Chess is a sport

I cannot believe it. There is so much hatred towards chess. Especially in my exercise science class. Those fools just refuse to accept that chess is a sport. Their argument hinges on the fact that chess is purely a mental activity whereas conventional sports (e.g soccer, basketball) are not.

However, Chess is well-measurable, ratable and just as competitive.

Well-measurable means that any position may be evaluated: one could decide the state of the game (whether its check or mate). But chess offers a bonus: one could provide a full or partial analysis as well (giving a sufficient amount of time). If chess wasn't well-measurable, it would be an art.

Chess strength can and is often measured by means of a rating system. Otherwise, it would be music. But for me, what makes chess a sport, is its inherent nature of competition. And believe me, chess competition is the bloodiest of all. Otherwise, it would be a performance.

Worth of note: Chess is a clocked game but is not exactly real time. Fast internet chess can cause players to develop RSI (Repetitive Strain Injury). Now that is a physical injury.

Posted by Oleg Ivrii, 06:26 PM / Comments (2)

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