Zugzwang

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Zugzwang is a position in which it is disadvantageous to move, as every move leads to a worse, and often lost position. Most of the time it happens in late endgames, specially pawn endings, the most obvious example being a KPK endgame, where opposition can be regarded as a special case of zugzwang.

Zugzwang and Null Move

Zugzwang positions are known cause the Null Move Pruning go wrong. For that reason most programs do not use null move in the late endings. As far as middlegame positions are concerned, programmers either assume that they happen too rarely to bother with them, or use some sort of verification pruning.

Mutual Zugzwang

Mutual or reciprocal zugzwang is a rare position such that who ever is to move is in zugzwang, which may occur in late endings [1].

Trébuchet

A Trébuchet is an extreme winning/losing type of reciprocal zugzwang in pawn endgames, also broached in Noam Elkies publication On numbers and endgames. [2].

See Also

Publications

[3]

Forum Posts

1999

Pseudo-code for verification search by Dan Homan, CCC, November 06, 1999

2000 ...

2010 ...

External Links

Zugzwang

Misc

References

  1. List of All Known Mutual Zugzwangs
  2. Noam D. Elkies (1999). On numbers and endgames: Combinatorial game theory in chess endgames. pdf, differs only in trivial stylistic details from the (1996) version published in Games of No Chance edited by Richard J. Nowakowski, MSRI Publications Volume 29
  3. ICGA Reference Database
  4. Zugzwang Test Suite ZPTS by Robert Allgeuer by Paul Henri, CCC, February 12, 2014
  5. Zugzwang Test Suite ZPTS - updated version and results of Fruit by Robert Allgeuer, CCC, October 19, 2004

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