Chess: Man vs. Machine Plays Out

Tania Hershman Email 10.21.02

HAIFA, Israel -- As world chess champion Victor Kramnik sat down to play the Deep Fritz chess program in Bahrain this week, Haifa University held a two-day symposium to address one question: What's the point of all this computer chess?

Back in 1997, IBM's Deep Blue beat world champion Garry Kasparov amid much fanfare.

2002 is a big year for computer chess, with the best human players taking up the challenge for the first time since Kasparov's defeat. Following Kramnik vs. Deep Fritz, in December Kasparov will try again against Deep Junior, the reigning International Computer Games Association world computer chess champion, in Jerusalem. (Controversially, Deep Fritz did not compete in the ICGA championship, but beat Deep Junior in a separate match in April 2001 to earn the right to play Kramnik.) A million dollars is at stake in each game.

So why wasn't the Kasparov-Deep Blue match enough to settle the issue of who's superior, humans or machines?

"As a scientist, a single data point that is unrepeatable (because Deep Blue has since been dismantled) is useless," said Jonathan Schaeffer of the University of Alberta Department of Computer Science's Games Group at the symposium, Man vs. Machine: The Experiment. "Now we have two more matches ... and we will get new data to see whether the machine is better than the man."

Brute force search has been the strength of the chess computer. Deep Blue processed 200 million positions per second.

But grandmasters don't play that way. They instantly discount bad moves, considering only good ones -- and psychologists are attempting to model how they do this.

Fernand Gobet, a psychologist from the University of Nottingham who specializes in intelligent systems, spoke in a videoconference about the chunking theory. It postulates that a grandmaster sees the chessboard as patterns or "chunks" of pieces, then as groups of these chunks -- not as individual pieces.

Such research may help software developers who are progressing from brute force search to something more sophisticated.

Deep Junior, authored by Israelis Amir Ban and Shai Bushinsky, has already implemented move-evaluation measures. Junior operates at a "depth" of 15 -- computer chess parlance for seeing 15 moves ahead.

"Junior measures depth in a different way to other programs," said Bushinsky during the symposium's exhibition match between Israeli international grandmasters, each using Junior as an assistant. (The match ended in a draw.)

"Junior counts plain, ordinary moves as two, while an interesting move is one or even less," Bushinsky said. "Fifteen is the weight of all the moves along the line."

Opponent modeling is another tactic.

"Sometimes the best move objectively is not the best move in a particular game, if you know your opponent's weaknesses," said Jaap van der Herik of Maastricht University's Institute for Knowledge and Agent Technology.

Several research groups are working on this, and it is proving "very, very difficult," said van der Herik. "(You are trying to) model your opponent's thought and follow the strategy your opponent is following." If it is possible, he suggested, then perhaps other "opponents" in, say, the political arena could also be modeled. In other words, a computer could run for election.

But will any of these developments persuade people to call a computer "intelligent"? Jonathan Schaeffer, for one, thinks it's possible.

"My (chess) program doesn't meet my definition of intelligence," Schaeffer said. "It plays chess but it can't do anything else. You need a program that is capable of solving more than one problem -- not just games but driving a car, writing a poem, carrying on a day-to-day conversation."

Schaeffer, who is the author of the world-champion checkers computer program, believes that researchers should broaden their game-playing horizons.

"If you want to understand intelligence, the game of Go is much more demanding," he said. "It doesn't have the silver bullet: deep search. Chess has somewhat outlived its usefulness. It turned out to be easier than we thought."

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