The man-versus-machine chess showdown remained deadlocked Wednesday as world champion Garry Kasparov and the IBM supercomputer Deep Blue drew their second game in a row.
After one win each and two draws, the score of the six-game match in Philadelphia stands at 2-2.
Kasparov, surprised by the intensity of the battle with a computer that calculates hundreds of millions of moves per second, acknowledged that he was drained by the first four games. After Wednesday's game, he said, "I'm exhausted. I'm dead."
On Wednesday, Kasparov obtained a small advantage with the White pieces but could not make progress. When Deep Blue's operator temporarily lost contact with the computer, Kasparov was visibly upset. "It was a crucial moment of the game. You're so full of all these emotions and it's difficult to control yourself."
At move 33, Kasparov devised a plan to capture Black's vulnerable c-pawn. He attained that goal two moves later but Deep Blue had foreseen that it could recover the lost pawn and another.
Kasparov's inaccuracy squandered his advantage and left Deep Blue with marginally the better position. Nevertheless, Kasparov was not in serious danger of losing the game, as Deep Blue could not maintain its extra pawn. Kasparov's draw offer at move 41 was rejected, but a move later, Kasparov's sacrifice of Rook for Knight enabled him to set up an impregnable defensive formation. Murray Campbell, one of Deep Blue's programmers, offered the draw at move 50.
It appears that Kasparov will need to gain a substantial advantage in the opening to score his second win. Deep Blue cannot formulate the long-range strategy needed to handle the opening, so it relies on its memory bank containing the opening moves of thousands of human games.
Here are the moves of Wednesday's game:
Kasparov-Deep Blue No. 4: 1 Nf3 d5 2 d4 c6 3 c4 e6 4 Nbd2 Nf6 5 e3 Nbd7 6 Bd3 Bd6 7 e4 dxe4 8 Nxe4 Nxe4 9 Bxe4 0-0 10 0-0 h6 11 Bc2 e5 12 Re1 exd4 13 Qxd4 Bc5 14 Qc3 a5 15 a3 Nf6 16 Be3 Bxe3 17 Rxe3 Bg4 18 Ne5 Re8 19 Rae1 Be6 20 f4 Qc8 21 h3 b5 22 f5 Bxc4 23 Nxc4 bxc4 24 Rxe8+ Nxe8 25 Re4 Nf6 26 Rxc4 Nd5 27 Qe5 Qd7 28 Rg4 f6 29 Qd4 Kh7 30 Re4 Rd8 31 Kh1 Qc7 32 Qf2 Qb8 33 Ba4 c5 34 Bc6 c4 35 Rxc4 Nb4 36 Bf3 Nd3 37 Qh4 Qxb2 38 Qg3 Qxa3 39 Rc7 Qf8 40 Ra7 Ne5 41 Rxa5 Qf7 42 Rxe5 fxe5 43 Qxe5 Re8 44 Qf4 Qf6 45 Bh5 Rf8 46 Bg6+ Kh8 47 Qc7 Qd4 48 Kh2 Ra8 49 Bh5 Qf6 50 Bg6 Rg8, Drawn.