Is this week's chess rematch between Garry Kasparov and a computer, a battle for humanity or one man's need for revenge, asks Shane Hegarty.
It has not been a good five years for Garry Kasparov and on Thursday night things took a turn for the worse. This week the chess great has finally been given a chance to avenge his 1997 defeat at the hands of a computer, Deep Blue.
He won the first game against the latest computer program, drew the second when he should have won, and two nights ago lost a game he should have drawn.
A glaring error when the match seemed destined for stalemate allowed his opponent, Deep Junior, to pounce, and level the series with five games to go.
"It makes the greatest player of all time look very human," commented one watching grandmaster. For Kasparov, it may have induced a nasty sense of déjà vu.
It was at this stage in his 1997 match against Deep Blue that Kasparov made a tactical error that so rattled him commentators felt it cost him not only that match, but the series. When Deep Blue emerged victorious, it stunned both the world and Kasparov, who had survived two previous encounters.
Developers IBM retired Deep Blue after that win, depriving a furious Kasparov of a rematch.
He may still be ranked the world number one, and is still something of a chess legend, but since that defeat Kasparov has lost both his air of invincibility and the world championship. In 2000, the title he had held continuously for 15 years was snatched from him by his one-time protégée Vladimir Kramnik.
Then in September of last year, he was beaten by a woman for the first time. When defeated in a single match by 24-year-old Hungarian Judit Polgar, he felt so humiliated that he walked away from the table mid-move, escaping to a passageway where photographers and journalists were barred. It proved sweet revenge for Polgar, previously called a "circus puppet" by Kasparov who had also said that female chess players should stick to having children.
Polgar had refused to speak to Kasparov since a previous match in which TV cameras caught the world number one illegally changing his mind on a move after he had quit the piece.
Because he is so eager to challenge a computer again, Kasparov has yet to follow the leads of world champions in other games. The world draughts champion, Ron King of Barbados, refuses to play the leading computer program Chinook in a proper title match. Meanwhile, the Scrabble community has barred computer programs from its tournaments.
However, an element of self-preservation has crept into the chess world. When the current world champion Vladimir Kramnik played leading chess engine Deep Fritz in Bahrain last October, it was only because the match promoter held a qualifying event without inviting the strongest computer programs. It caused uproar on Internet chess forums, who were further annoyed by the organisers' handicapping of Deep Fritz in asking its programmers to freeze its code several months before the start, and not make any program changes. Kramnik was also given a copy of the program in advance, so had time to practise against it. He could adjourn a game after 56 moves, and "ask" it what its next move might be. Despite all the advantages, Kramnik only drew the eight-game contest. The contest, in a world perhaps lacking a Don King figure, was billed "Brains in Bahrain".
Unlike his encounters with Deep Blue, Kasparov did have advance access to Deep Junior, a program that can process three million moves a second and that won its third world computer title last July. Kasparov will earn $500,000 for playing, and a further $300,000 if he wins. If he beats Deep Junior, he will become the first human to do so.
"After the other matches I felt hooked to be part of this competition because I believe it is very important for the game of chess and humanity as a whole," Kasparov said before the start. After defeating Deep Junior in the first game he mocked: "I think we have quite some time before being wiped out by machines."
Deep Junior's Israeli programmers don't want to wipe out humanity, they just want to win a game of chess. If that happens it will mark another step on the road of artificial intelligence, but without quite the same shock as delivered in 1997. Kasparov's need for a rematch, so, may be less about a battle for humanity and more about one man's need for revenge.
"Is this 'idiocy'? Or something so brilliant that it just 'looks' stupid?" he once commented on a chess move. A win this week will go a long way to answering that question.
Follow Kasparov v Deep Junior at www.chessbase.com. Match 4 is on tomorrow, from 8.30 p.m. GMT.