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Blitzing to win at computer chess.

Blitzing to win at computer chess

It took more than speed and processing power to win the world computer chess championship this week in Cologne, West Germany. After its first two games in a five-game tournament, CRAY BLITZ, the defending champion, was in trouble. It has just lost a game to a lightly regarded opponent. But a mid-tournament correction--the removal of four lines in a 28,000-line computer program -- saved the day and the title. CRAY BLITZ became the first program in the tournament's 12-year history to repeat as world champion. In the tournament, four of the 23 competing chess computers finished at the top with identical 4-win and 1-loss records. CRAY BLITZ won the championship over Hitech, BEBE and Sun Phoenix in a tie-breaking scheme.

CRAY BLITZ's initial problems stemmed from four lines that program developer Robert Hyatt, a graduate student at the University of Alabama in Birmingham, had inserted after testing some parts of his program on a VAX minicomputer and finding an apparent weakness in the way the computer evaluated pawn movements. But when the modified program was run on a CRAY supercomputer, which is fast enough to allow a much deeper search than a VAX, the effect was not unlike "putting glue on the bottoms of all the pawns," says Hyatt. That change probably led to the losses at last year's North American computer chess championship (SN: 10/26/85, p.260) and this tournament.

But after the offending lines were removed, CRAY BLITZ started playing like a world champion again. "The difference in its play was striking," says Hyatt. The program swept through its next two games and seemed ready for its climactic match with favored Hitech, developed by Hans Berliner and his colleagues at Carnegie-Mellon University (CMU) in Pittsburgh.

The match took more than six hours. After about 60 moves, Hitech finally resigned. "We could feel it slowly slipping away," says CMU's Murray Campbell. But, he adds, "we're looking for our revenge in Dallas." That's where the North American computer chess championship will be decided in November.
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Author:Peterson, Ivars
Publication:Science News
Date:Jun 21, 1986
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