Chess

The humans fought back in the fifth round of the Aegon Man versus Machine tournament in The Hague winning, according to the official press release, "convincingly by the narrowest margin". Oxymoronic it may be, but when you've just been beaten by 301/2-171/2, even a 241/2-231/2 win must feel convincing.

Nevertheless, the machines still lead by the convincingly large margin of 130-109 with only one round left to play.

The following games show some of the strengths and weaknesses of computer chess.

In the first, the machine looks hesitant with 10.Be2 and 11.Bd3, but its h-pawn charge immediately afterwards is quite the opposite.

With 14...Bh6 inviting such problems as 15.e5 fxe5 16.Rxh6 Nxh6 17.Bxg5, Nunn retreated his bishop, only to run into the brilliant 16.Nxd5! After 16...exd5 17.Bxh7+! Kxh7 18.Qd3+ Kg8 19.Qg6+ Black is mated.

The next blow was 19.Bxg5! which would have been an imaginative and speculative sacrifice had a human played it, but the machine probably had it all worked out - at least as far as 25.e5, when it was clear Black was lost.

The finish was neat with 33.Bxb5 threatening Qd8 mate, and 34.Be8 planning 34...Rf5 (34...Qf5+ is met by 35.Kb3) 35.Qd7+ Kf6 36.Q g7 mate.

White: Quest

Black: John Nunn

1 e4 g6 18 Rh5 Rf7

2 d4 Bg7 19 Bxg5 Bxf3

3 Nc3 c6 20 gxf3 fxg5

4 Nf3 d5 21 Rxg5+ Kf8

5 h3 Nh6 22 Rdg1 Nf6

6 Bf4 f6 23 Ne4 Ndxe4

7 Qd2 Nf7 24 fxe4 Qxd4

8 0-0-0 0-0 25 e5 Ke7

9 Be3 a6 26 c3 Qb6

10 Be2 b5 27 exf6+ Bxf6

11 Bd3 e6 28 Rg8 Rxg8

12 h4 Nd7 29 Rxg8 Bh4

13 h5 g5 30 f4 Bf2

14 h6 Bh8 31 Kc2 Qe3

15 exd5 cxd5 32 Qd1 Qxf4

16 Nxd5 Bb7 33 Bxb5 Bb6

17 Nc3 Nd6 34 Be8 resigns

Here's a small measure of revenge for humankind:

White: Virtua Chess

Black: Zsuzsa Polgar

1 e4 e5 15 Qc6 Rd8

2 Nf3 Nc6 16 Ke1 Bg4

3 c3 d5 17 Bb2 Rd2

4 Bb5 dxe4 18 Qc4 Rxb2

5 Nxe5 Qd5 19 Rc1 Re2+

6 Qa4 Qxe5 20 Qxe2 Bxe2

7 Bxc6+ bxc6 21 Kxe2 Qh5+

8 Qxc6+ Kd8 22 Ke1 Ng3

9 Qxa8 Nf6 23 Kf2 Nxh1+

10 Na3 Bc5 24 Rxh1 Qf5+

11 b4 Bxf2+ 25 Ke2 Qd5

12 Kxf2 e3+ 26 Ra1 Qxg2+

13 dxe3 Ne4+ White resigns

14 Ke2 Ke7

William Hartston