Tim came to the club buzzing with these a few weeks ago.
(German: forced move) is a chess position where, if it's your turn to move, you lose, and if your opponent has the move, you might be OK.
Here's an example from one of my own games: anything White does loses. We say, White is in Zugzwang
Black can doodle happily with pawn moves, but any move of a white Pawn or piece loses at least a Pawn. White in fact threw himself on the sword with
43. c4 Ra3+ 44. Kh4 Be7+ 45. Kh5 Rh3#
The simplest Zugzwang position of all is known from the theory of Pawn endgames, with two Kings and one pawn trying to promote.
Black to move loses, but with White to move, it's a draw.
or reciprocal Zugzwang is where neither side wants to move, and this position is indeed a mutual Zugzwang.
A mutual full-point Zugzwang
(m-f-p-Z) is where both
sides are in Zugzwang. In the Pawn endgame, White to move concedes a half-point to Black, but in a m-f-p-Z White loses a whole point. Here's an example, known as the trebuchet
All OK? So
, these ideas have been around for dickey's years
, but what Tim was enthusiastic about was learning of positions with King each, a Pawn each and a single white piece (Bishop, Knight or Rook), which met the conditions of a m-f-p-Z. In fact, Tim was more mischievous than just to show us: he set us the task of finding the positions! I'll give you an hour or so now to have a go yourselves...
Finished? How many did you get?
Solutions for 5-men positions:
A couple with a Knight:
Nothing so simple exists for a Queen, but if you are prepared to add extra pawns, or an enemy Queen:
Here are solutions for 6-men positions with B N or R:
And if you have a Rook each, we have examples like:
Article about 6-man tablebases:
John Nunn got a bit interested in all these, and I refer you to his excellent books based on comprehensive computer endgame databases, recently updated since the emergence of the 6-man tablebases:
Candidates for the Immortal zugzwang game include this classic from Nimzowitsch:
Samisch - Nimzovitch [E06] Carlsbad, 1923
And two he would rather forget:
Nimzovitch,A - Capablanca,J [B12] New York, 1927
Alekhin - Nimzowitsch [C17] San Remo, 1930
All are to be found in the Canon: