Chess vs. Chess960: A PC's View

Chess960 seems to hold special appeal for chess programmers. Because the placement of pieces is random, computers rely on lightning-fast processing, without retrieving archives of past moves from a database.

Conventional chess-playing programs, with their dreadful power to calculate moves deep into the future, still rely on a digital version of an opening book at the outset of each game. This is essentially a look-up table constructed by a specialist, dictating the correct move for two million or more unique positions.

The drawback of this approach went on spectacular display last year in a computer-versus-computer match in the Netherlands pitting a strong PC-based commercial chess program called Shredder against Hydra, a fearsome 16-processor supercomputer built from the ground up for chess.

Shredder should have been lucky to get a draw against Hydra's custom hardware. But it didn't work out that way. Both systems played from their books for 27 moves, and it turned out the book play, despite having been transcribed from a grandmaster game, held hidden danger for black that human players had missed.

When Shredder and Hydra began thinking for themselves on the 28th move, both systems quickly calculated Hydra's inevitable defeat. Hydra's operator resigned three moves later. The game was essentially lost before the supercomputer performed a microsecond of analysis.

"He played according to his opening book, which was bad, so he lost," Stefan Meyer-Kahlen, Shredder's programmer, said of his digital adversary. "That's the disadvantage in an opening book....The programs are so strong that there may be mistakes that the grandmasters haven't noticed, but the computers noticed."

That can't happen with Chess960, which lets a chess program skip the part where it's acting as little more than a database engine. Last week, Meyer-Kahlen released a new version of Shredder that knows how to play Fischer's game, and he's enrolled it in next month's computer tournament. It is considered one of two favorites to win. (The other contender is a commercial program called HIARCS, known for its strong positional play.)

Adapting his program to play Chess960 was a relatively simple matter, Meyer-Kahlen said, but other programmers have discovered some unexpected twists in the process. Richard Pijl, the Netherlands-based coder behind a free program called the Baron, said that without an opening book to guide it, his software initially had trouble discovering the basic concept of "developing" its pieces -- bringing the bishops and knights into action at the beginning of the game.

Shoring up that weakness had the side effect of making the Baron stronger in conventional chess, he said. (The Baron also easily embarrassed a Wired News reporter in a Chess960 game.)

In all, 21 programs, with names like Xinix, Spike and Quark, are joining the Baron, Shredder and HIARCS on the field of battle Aug. 11 and 12 at the first Chess960 Computer World Championship in Mainz, Germany. That makes the contest more of a draw than the standard Computer Chess World Championship, held last year in Tel Aviv, which brought in only 14 contestants.