Sunday, February 25, 2007

Study time

In a recent issue of Chess Today GM Alex Baburin looked at some endings in which a lone bishop must contend with a knight plus two pawns that are separated by one file. If the defender's king is on scene a surprisingly large proportion of these endings cannot be won for the stronger side.

Baburin's article caused me to recall a 1929 study by the Soviet composer A. Gurvich, which is shown in the diagram. This study has been republished in a number of places, most notably Volume 5 of the Encyclopaedia of Chess Endings from Chess Informant as well as the Chess Endgame Training CD from Convekta.

Endgame studies are a fascinating branch of chess creativity. The stipulation – White to play and win or White to play and draw – usually if not always looks impossible of achievement but closer examination will reveal a tactical solution that eventually overcomes all resistance. In the best studies a forcing line of play will appear to hit a dead end several moves along but then a new tactic that has arisen as if by chance will allow further progress to be made. There is no better way of increasing one's powers of combination and calculation than solving endgame studies. For best results I recommend setting up the position on a board but not allowing yourself to move the men. In fact I suggest you do that here before reading further. To help with this I have not set the moves of the solution in bold type.

In Gurvich's study White is called upon to win against any defence. This looks typically impossible because Black is threatening to capture the h-pawn and then give up his bishop for the f-pawn. A lone knight cannot deliver mate so White must prevent this plan. The only way forward is 1.Nh5+ since 1...Kxh7 loses the bishop after 2.Nf6+. Black must therefore play 1...Kh8.

White must now be careful. Both 2.f6 and 2.Kf6 fail to 2...Kxh7 since the knight check is now blocked. 2.Kg6 is met by 2...Be4! 3.Nf6 Bd3 (or 3.Bc2) and White cannot make further progress since any move of the knight runs into ...Bxf5 followed by capturing the h-pawn with either king or bishop according to circumstances. So White must play 2.Kh6, protecting his pawn. This has the added virtue of threatening 3.Nf4 followed by 4.Ng6 mate.

Black has two moves to counter this plan: 2...Bf7 and 2...Be4. The first one is overcome in prosaic fashion after 3.Nf4 Be8 4.f6 Bf7 5.Nd3! Bg6 6.Ne5 Be8 (or 6...Bxh7 7.f7 Bg8 8.Ng6 mate) 7.f7 Bxf7 8.Nxf7 mate. The second move is more difficult to meet but a little reflection reveals that White must push his f-pawn with 3.f5. Everything else allows Black to force a draw with 3...Bxf5. This includes 3.Ng3 Bxf5! since 4.Nxf5 is stalemate.

After 3.f6 Black of course must take on h7 – otherwise White wins as in the line with 2...Bf7 that we looked at earlier. So 3...Bxh7 and now 4.f7 looks quite deadly. But Black is not done yet: 4...Bg8! threatens to take the pawn and force a draw, and if White promotes to a queen (or rook) Black is again stalemated.

We have reached the culminating point of the study. White must promote his pawn to either a bishop or a knight. It is well known that two knights can deliver mate only in exceptional circumstances, which do not apply here since Black has a bishop standing ready to prevent the mating move. So the only move left is 5.f8=B. Black is now free to move his bishop anywhere he likes, but in every case White will reply with 6.Nf6! This takes away the king's flight square on g8 and threatens an unstoppable 7.Bg7 mate, thus satisfying the stipulation. All of White's pieces are on dark squares so without the stalemate factor Black's bishop may as well be on another board!

To those interested in delving further into the wonderful world of endgame studies I can recommend two books: 1234 Modern End-Game Studies by Harold Lommer and Test Tube Chess by John Roycroft. Both are available in Dover reprints and should be relatively easy to obtain.

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Port Coquitlam, British Columbia, Canada
National master (Canada) since 1984. B.C. Champion 1977 and 1984. Runner-up 1991 and 2002. B.C. Open Champion 1972 and 1982. B.C. U/14 Champion 1964-65-66. Mikhail Botvinnik once wrote that publishing your analytical work forces you to be accurate because it exposes you to criticism. Hence this blog.