Kasparov's blunder in 1997 game six against deep blue:
Somewhat atypically, Kasparov plays the solid Caro-Kann Defense. In later matches against computers he opted for 1...e5 or 1...c5, the sharp Sicilian Defense, Kasparov's usual choice against human opponents.
2.d4 d5 3.Nc3 dxe4 4.Nxe4 Nd7 5.Ng5
This relatively recent innovation breaks one of the classic opening principles ("don't move the same piece twice in the opening"
, but puts pressure on the weak f7 square. Kasparov had played this move himself as White at least three times earlier.
Not 5...h6? 6.Ne6! fxe6?? 7.Qh5+ g6 8.Qxg6#.
6.Bd3 e6 7.N1f3 h6??
A strange blunder by Kasparov, one of the most theoretically knowledgeable players in chess history. Apparently Kasparov got his opening moves mixed up, playing ...h6 a move too early. The normal
7...Bd6 8.Qe2 h6 9.Ne4 Nxe4 10.Qxe4 was played in Kasparov(!)-Kamsky, 1994 and Kasparov-Epishin, 1995, among other games. The upcoming sacrifice is well known to theory and Kasparov must have known about it (in fact, there are some reports that he even wrote an article supporting 8.Nxe6 as a refutation).
Actually it is not Deep Blue's fantastic skills which made it play this move, the knight sacrifice is programmed into the computer's opening book. This move had been played in a number of previous high-level games, with White achieving a huge plus score.
Instead of taking the knight immediately, Kasparov pins the knight to the king in order to give his king a square on d8. However, many annotators have criticized this move and said that Kasparov ought to have taken the knight immediately. Although the Black king uses two moves to reach d8 after 8...fxe6 9.Bg6+ Ke7, the Black queen can be placed at the superior c7 square.
White castles so that 9...Qxe6?? loses to 10.Re1 pinning and winning the black queen. Black must now take the knight or he will be a pawn down.
9...fxe6 10.Bg6+ Kd8 11.Bf4
If Black's bishop were on d6 instead of f8, White would not be able to play this. For the sacrificed knight, White's bishops have a stranglehold on Black's position. Black, having moved his king, can no longer castle, his queen is blocking his own bishop, and he has trouble getting out his pieces and making use of his extra knight.
The first new move of the game and Deep Blue must now start thinking on its own. Kasparov's idea is to get some breathing room on his queenside and prevent White from playing c4.
12.a4 Bb7 13.Re1 Nd5 14.Bg3 Kc8 15.axb5 cxb5 16.Qd3 Bc6 17.Bf5
White is pounding at Black's e6 pawn and is planning to invade the position with his rooks. Kasparov cannot hold onto all his extra material and desperately decides to surrender his queen for a rook and a bishop.
17...exf5 18.Rxe7 Bxe7 19.c4 Black Resigns
Black resigns because the white queen will soon invade through c4 or f5, and once Re1 is played it will be lights out. A sample line would be: 19...bxc4 20.Qxc4 Nb4 (20...Kb7 21.Qa6 mate!) 21.Re1 Kd8 22.Rxe7 Kxe7 23.Qxb4+. The shortest loss of Kasparov's career.
After the game Kasparov was in a foul mood and accused the Deep Blue team of cheating (i.e. having a team of human masters to aid the computer). Although Kasparov wanted another rematch, IBM declined and ended their Deep Blue program.