Chess

THE EXEMPLARY battle for first place in Arnhem ended in a tie on Saturday after Matthew Sadler and Viktor Korchnoi won their last round games against Xie Jun and Friso Nijboer respectively. This gave them both 4/6, clear of Nijboer on 2.5 and Xie Jun on 1.5.

With two rounds to go Korchnoi had led by half a point. But things turned round on Friday when Xie Jun scored a nice victory against Korchnoi, who seemed to overpress as Black in his favourite French Defence, while Sadler came within a whisker of victory against Nijboer.

White: Firso Nijboer

Black: Matthew Sadler

Although stalemate intervenes in an attempt to mate with two knights against a bare king, extra pawn(s) paradoxically help Black.

And in fact Ken Thompson, of AT&T Bell Laboratories' endgame databases on CDRom, informs us that after 63...Nxb6 it is "checkmate mate in 17 moves".

The Sadler/Korchnoi game continued on the following lines: 63.b6! Nxb6 64.Ka6 Nc4 65.Kb7 Kd6 66.Kc8 Na5 67.Kd8 Nb7+ 68.Ke8 Ke6 69.Kf8 Nbd6 70.Kg8 Ke7 71.Kh7 Kf7 72.Kh8 Kg6? 73.Kg8 Nf7 74.Kf8 N7h6 75.Ke8...

Play up to 70...Ke7 was perfect but the CDRom gives: 70...Ne8 71.Kh8 Ke7 72.Kg8 Neg7 73.Kh7 Kf6 74.Kg8 Ne6 75.Kh7 Kf7 76.Kh8 Kg6 77.Kg8 Ne7+ 78.Kh8 Kh6 79.f5 Ng5 80.f6 Nf7 mate. 72...Ne8 73.Kh7 Neg7 would have led to the same thing.

After 113 moves the game reached the second diagram, at the top of the next column.

After 113...Ne3, Nijboer was, luckily for him, able to claim a draw under the 50-move rule. If 114.Kg1 Kg3 115.f5 Nh3+ 116.Kh1 Ng4 117.f6 Ngf2 is mate. So without this escape, he would have had to "reset the move counter" with 114.f5 when White has another 50 moves, and in fact the AT&T Bell Laboratories endgame database CDRom gives the following outcome.

Neg4+ 115.Kg1 Nf6 116.Kh2 N2e4 117.Kh3 Kf2 118.Kh4 Ke2 119.Kh3 Kf3 120.Kh4 Kf4 121.Kh3 Nd2 122.Kg2 Ke3 123.Kg1 Ke2 124.Kh1 Kf2 125.Kh2 Nf1+ 126.Kh3 Kf3 127.Kh4 Kf4 128.Kh3 Ne3 129.Kh4 Ng2+ 130.Kh3 Kf3 131.Kh2 Nf4 132.Kg1 Ke2 133.Kh2 Kf2 134.Kh1 Ng4 135.f6 Nh5 136.f7 Ng3 mate.