BONN, Germany: One of the many differences between human beings and computers is that computers do not have blind spots, as world chess champion Vladimir Kramnik did in game two of his match against the Deep Fritz software on Monday.
After outplaying the machine for most of the game, and with a clear draw in hand, he made a colossal blunder that allowed checkmate on the move.
Deep Fritz now leads the six-game match, 1.5-0.5
"It was very strange to me. I cannot find an explanation," Kramnik told reporters after the game. "I was not tired." He looked remarkably calm and composed despite the loss.
Time pressure was not a factor. Kramnik had 33 minutes to make five moves when he went over the cliff.
The machine's handlers chose to open with the queen pawn (the program's opening book is set before the match) and Kramnik responded with the Queen's Gambit Accepted, a solid line that fits his style and avoids the computer's advantages.
After fifteen moves, American grandmaster Yasser Seirawan said that Kramnik was "in no danger." Kramnik had the advantage on the queenside and Fritz's chances on the kingside seemed illusory.
In the moves that followed, Kramnik obtained a two-on-one queenside pawn majority. He allowed the f-file to be opened and allowed his f-pawn to fall to a queen check. But his king seemed safe in the corner on h8.
Still, the machine seemed to have enough play to hold the position. According to its operator, Mathias Feist, Fritz rated itself down two-thirds of a pawn.
Kramnik said afterward, "My position was simply better without any risk."
On move 31, Kramnik pushed his a-pawn, perhaps prematurely, and entered a series of forced moves that should have ended in a draw. It seems likely that Kramnik had already calculated the line they were to follow, only without noticing the checkmate threat ahead.
Kramnik could have avoided the checkmate by simply moving his king and the game would have quickly ended in a draw. Instead, he moved his queen, offering to exchange queens into an ending that his a-pawn would have quickly decided in his favor.
Unfortunately, he completely overlooked the checkmate. Seirawan pointed out that delivering checkmate was the only move that did not lose for the computer.
The blunder, which Seirawan called "a tragedy," was one that even the weakest amateurs would not ordinarily make and almost unheard of at this level.
The first game of the match was drawn on Saturday. Kramnik achieved a considerable advantage and some observers, notably former world champion Garry Kasparov, felt that Kramnik may have missed a winning continuation.
Game three is scheduled for Wednesday. Kramnik will have White.
On the Net:
1. d4 d5 2. c4 dxc4 3. e4 b5 4. a4 c6 5. Nc3 b4 6. Na2 Nf6 7. e5 Nd5 8. Bxc4 e6 9. Nf3 a5 10. Bg5 Qb6 11. Nc1 Ba6 12. Qe2 h6 13. Be3 Bxc4 14. Qxc4 Nd7 15. Nb3 Be7 16. Rc1 O-O 17. O-O Rfc8 18. Qe2 c5 19. Nfd2 Qc6 20. Qh5 Qxa4 21. Nxc5 Nxc5
22. dxc5 Nxe3 23. fxe3 Bxc5 24. Qxf7+ Kh8 25. Qf3 Rf8 26. Qe4 Qd7 27. Nb3 Bb6 28. Rfd1 Qf7 29. Rf1 Qa7 30. Rxf8+ Rxf8 31. Nd4 a4 32. Nxe6 Bxe3+ 33. Kh1 Bxc1 34. Nxf8 Qe3 35. Qh7 checkmate