chess

The paradoxical thing about computers playing chess is that the positions that seem most complicated to humans are actually the simplest for computers, and vice versa. Where potential captures, checks, threats and hazards combine in mind-numbing profusion, the machine can compute, with no possibility of error, all the forcing sequences that make our heads spin. Yet when the two armies disengage, and the position simplifies to a state of tactical quiescence, the machine is liable not to have the faintest idea what to do. It can calculate billions of variations, but none leads to anything concrete.

Kasparov's third game against Deep Blue, which ended in a draw, gave a good picture of the basic differences between man and machine. No human would so willingly have given up control of the Q-side white squares as Deep Blue did, yet few would have found the excellent plan of 20.Rcb1! and 21.Bb8! which let it fight its way back into the game.

White: Deep Blue

Black: Garry Kasparov

1 e4 c5 2 c3 d5 3 exd5 Qxd5 4 d4 Nf6 5 Nf3 Bg4 6 Be2 e6 7 0-0 Nc6 8 Be3 cxd4 9 cxd4 Bb4 10 a3 Ba5 11 Nc3 Qd6 12 Ne5 Bxe2 13 Qxe2 Bxc3 14 bxc3 Nxe5 15 Bf4 Nf3+ 16 Qxf3 Qd5 17 Qd3 Rc8 18 Rfc1 Qc4 19 Qxc4 Rxc4 20 Rcb1 b6 21 Bb8 Ra4 22 Rb4 Ra5 23 Rc4 0-0 24 Bd6 Ra8 25 Rc6 b5 26 Kf1 Ra4 27 Rb1 a6 28 Ke2 h5 29 Kd3 Rd8 30 Be7 Rd7 31 Bxf6 gxf6 32 Rb3 Kg7 33 Ke3 e5 34 g3 exd4+ 35 cxd4 Re7+ 36 Kf3 Rd7 37 Rd3 Raxd4 38 Rxd4 Rxd4 39 Rxa6 draw.