Independent Pursuits: Chess

FOR THE last Monday of the year an endgame theme seemed in order; and why not go to the end of the alphabet too, with that essential concept zugzwang?

Now adopted into English from the original German, zugzwang is applied to a position in which, in contrast to the normal situation, it is a disadvantage to be on move. Sometimes one side can manoeuvre to put the other "into zugzwang" even if originally they had the move. But in other cases, this is impossible: so-called "mutual zugzwang", as in this, the fundamental position of all endgame play.

Mutual zugzwang, White to play

1 d7+

If 1 Ke5 Kd7 2 Kd5 Kd8! draws - but not 2... Ke8?? 3 Ke6 when it's now Black's move.

1... Kd8 2 Kd6 stalemate

Whereas with Black to move 1... Kd8 2 d7 Kc7 3 Ke7 wins.

See next diagram: In this much more difficult position, White starts off apparently in zugzwang but is able to "lose a move" to (threaten to) reach the same position, but with

Triangulation

his adversary on play. The method here is called "triangulation" after the White king march from d4-c4-d5. Black cannot follow suit since his king can't go to d7.

1.Kd5 Kc8 2.Kd4 Kd8 3.Kc4 Kc8 4.Kd5 Kd8 5.Kd6 Kc8 6.c7 and wins

White to play and win

Richard Reti 1922

Both the first two examples were rather dry and technical. Not so this beautiful study. Black is threatening to draw with 1... Kb5. The solution is just two exquisite moves:

1 Nd4+ Kc5 2 Kh1!! zugzwang