Computer chess built in by the evaluation function and pruning/extension rules began to match the best players in the world. It turned out to produce excellent results, at least in the field of chess, to let computers do what they do best (calculate) rather than coax them into imitating human thought processes and knowledge. In 1997 Deep Blue defeated World Champion Garry Kasparov, marking the first time a computer has defeated a reigning world chess champion in standard time control. Computer chess programs consider chess moves as a game tree. In theory, they examine all moves, then all counter-moves to those moves,
Human–computer chess matches points. Humans won 148 ½ points. Yona Kosashvili scored highest for the humans at 6 points out of 6 games. Kallisto scored highest for the computers at 4 ½ points. In 1988, Deep Thought shared first place with Tony Miles in the Software Toolworks Championship, ahead of a former world champion Mikhail Tal and several grandmasters, including Samuel Reshevsky, Walter Browne, and Mikhail Gurevich. It also defeated grandmaster Bent Larsen, making it the first computer to beat a grandmaster in a tournament. Its rating for performance in this tournament of 2745 (USCF scale). In 1989, Levy was defeated by the