Deep Blue was a chess-playing computer developed by IBM. On May 11, 1997, the machine, with human intervention between games, won the second six-game match against world champion Garry Kasparov by two wins to one with three draws. Kasparov accused IBM of cheating and demanded a rematch, but IBM refused and dismantled Deep Blue. Kasparov had beaten a previous version of Deep Blue in 1996. On February 10, 1996, Deep Blue became the first machine to win a chess game against a reigning world champion (Garry Kasparov) under regular time controls. However, Kasparov won three and drew two of the following five games, beating Deep Blue by a score of 4–2 (wins count 1 point, draws count ½ point). The match concluded on February 17, 1996. Deep Blue was then heavily upgraded (unofficially nicknamed “Deeper Blue”) and played Kasparov again in May 1997, winning the six-game rematch 3½–2½, ending on May 11. Deep Blue won the deciding game six after Kasparov made a mistake in the opening, becoming the first computer system to defeat a reigning world champion in a match under standard chess tournament time controls.