Serious work on machines that play chess has been going on since 1890, and chess-playing computer programs featured prominently in the artificial intelligence boom of the 1950s - 1970s. At first considered only a curiosity, the best chess playing programs — like Shredder, Fritz etc. — have become extremely strong players. In blitz chess, they can beat the best human players; at regular time controls, however, battles between the very best chess programs and the very best human players have been tantalizingly finely balanced. However, it is important to note that the method by which computer programs play chess does not really resemble the way humans play chess — the computer basically just calculates the board position after every possible combination of legal moves and acts accordingly, whereas human masters act more from intuition and pattern recognition. Moreover, as CPU speed and memory become less expensive, computer chess programs can search ever larger numbers of moves in the same amount of time, and store ever larger databases of opening and endgame positions. Nor has the study of chess proven particularly useful in the broader AI field; the methods used to play high-level chess are very different to the ones used for machine learning, machine vision, and the like.
Garry Kasparov, then ranked number one in the world, played a six-game match against IBM's chess computer Deep Blue in February 1996. Deep Blue shocked the world by winning the first game in Deep Blue - Kasparov, 1996, Game 1, but Kasparov convincingly won the match by winning three games and drawing two. View 1997 Kasparov-Deep Blue games at our online chess database.
The six-game rematch in May 1997 was won by the machine (informally dubbed Deeper Blue) which was subsequently retired by IBM. In October 2002, Vladimir Kramnik drew in an eight-game match with the computer program Deep Fritz. In 2003, Kasparov drew both a six-game match with the computer program Deep Junior in February, and a four-game match against X3D Fritz in November.
The chess machine Hydra is the intellectual descendant of Deep Blue; and appears to be somewhat stronger than Deep Blue was. Certainly it is very much comparable in terms of positions analysed per second. Given the relative ease with which it beats the other programs, and the humans it has met, Hydra may be expected to beat any unaided human player in match play. In June 2005, Hydra scored a decisive victory over the then 7th ranked GM Michael Adams winning five games and drawing one game in a six game match. Whilst too few games have been played to establish this, and neither Kramnik or Kasparov have played Hydra, Hydra's creators estimate its rating should be over 3000.
Kasparov's loss to Deep Blue has inspired the creation of chess variants in which human intelligence can still overpower computer calculation. In particular Arimaa, which is played upon a standard 8×8 chessboard, is a game at which humans can beat the best efforts of programmers so far, even at fast time controls.