CHESS

Col Polhill explains a subtle principle of Grandmastery.

I have nothing against prophylaxis, but there's a time and a place for everything, and good preventive chess demands the subtlety of the Finchley Central Principle.

Played between gentlemen, the game of Finchley Central involves each in turn uttering the name of a station on the London underground railway, the only restriction being that no station may be used more than once. The winner is the first to utter Finchley Central.

It may seem that the player who starts may win immediately by saying "Finchley Central". Indeed he could were it not for the rule that the players must be gentlemen.

No, for a true gentleman the only time to say "Finchley Central" is the move before your opponent would have. Thus if only two unnamed stations remain, you may confidently say "Finchley Central" in the knowledge that your opponent would if you did not. If three stations remain, you may play FC, otherwise two would remain and your opponent would surely do so.

The implication is clear: the perfect time to do anything in life is the moment before somebody prevents it. In the Sicilian Defence, Black should push his pawn to b5 on the move before White stops it with a4. White, in turn, should play a4 on the move before Black would have played b5.

In today's game White displayed poor Finchley Cent-rality. His 14.Bb5+ prevented Black's castling. But was Kor-chnoi going to castle? I think not. 19.Rc2 defended c2, but was Viktor about to victimise the c-pawn? Not yet! Korch-noi's 22...Nd2!! (see diagram), with its threats of Rxd4 or Qc1+ prevented Rxd2, Rxh4 and Bd3, any of which White would have been delighted to play. Finally, after 24...Rc5, White could only prevent the intended Ra5+ by resigning. A Finchley Central to savour.

White: Maurice Ashley

Black: Viktor Korchnoi

San Francisco 1995

1.e4 c6 2.d4 d5 3.Nd2 dxe4 4.Nxe4 Bf5 5.Ng3 Bg6 6.Nf3 Nf6 7.Ne5 Nbd7 8.Nxg6 hxg6 9.Bd3 Qc7 10.Qf3 e6 11.Be3 c5 12.dxc5 Bxc5 13.Bxc5 Nxc5 14.Bb5+ Ke7! 15.0-0-0 Rh4! 16.Be2 Rc8 17.Kb1 b5 18.Qe3 b4 19.Rd2 Nce4 20.Nxe4 Nxe4 21.Rd4 Qxc2+ 22.Ka1 Nd2 23.b3 Nxb3+ 24.axb3 Rc5 White resigns.