Earlier this year, IBM celebrated the 15-year anniversary of its supercomputer Deep Blue beating chess champion Garry Kasparov. According to a new book, however, it may have been an accidental glitch rather than computing firepower that gave Deep Blue the win.

At the Washington Post, Brad Plumer highlights a passage from Nate Silver's The Signal and the Noise. Silver interviewed Murray Campbell, a computer scientist that worked on Deep Blue, who explained that during the 1997 tournament the supercomputer suffered from a bug in the first game. Unable to pick a strategic move because of the glitch, it resorted to its fall-back mechanism: choosing a play at random. "A bug occurred in the game and it may have made Kasparov misunderstand the capabilities of Deep Blue," Campbell tells Silver in the book. "He didn't come up with the theory that the move it played was a bug."

As Silver explains it, Kasparov may have taken his own inability to understand the logic of Deep Blue's buggy move as a sign of the computer's superiority. Sure enough, Kasparov began having difficulty in the second game of the tournament — and Deep Blue ended up winning in the end.