13

Although very unlikely, the starting position could be a forced win for black. This would mean it is a position of mutual zugzwang, in the strong sense that whoever moves first loses. Wikipedia (Link) refers to one such position as trébuchet. Such positions are rare, and it would be a big surprise if the starting position was one of them.

The starting position has another property: it is symmetric. White and black have exactly the same possible moves (when written in descriptive notation).

My question: Are there any symmetric positions that are known to be a mutual zugzwang?

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    Great question, thank you! Nit: I think the trebuchet is a specific example of full point Zugzwang (KPvKP) rather than a synonym for full point Zugzwang. – Laska Oct 11 '17 at 15:28
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    The trebuchet is symmetrical if you are playing on a 7x8 board! :D – Laska Oct 11 '17 at 15:29
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    @Laska I think maybe the wiki article has been updated and expanded since I asked this question. – Dag Oskar Madsen Oct 11 '17 at 19:49
21

You can easily construct many such positions. For instance:

4k3/8/3P1P/8/8/3p1p2/8/4K3 w - - 0 1

First to move loses - either by moving a king and allowing the opponent to promote or by losing one (and subsequently next) pawn.

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  • What about: Kd1 f2 Ke1 f1=Q Kxf1 d2 Ke1........ – OldBunny2800 Dec 2 '16 at 0:05
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    @OldBunny2800: Your king uses an invisibility cloak at Ke1 so the pawn at f2 can't see it? – user21820 Dec 2 '16 at 1:33
  • @user21820 ???? – OldBunny2800 Dec 2 '16 at 1:43
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    @OldBunny2800: Your suggestion in your comment is invalid because you moved the king into check. – user21820 Dec 2 '16 at 2:14
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    @user21820 ohhhh, my bad. – OldBunny2800 Dec 2 '16 at 3:04
5

In all The chess books I've read, "trébuchet" is actually one particular case of a full-point double-zugzwang: the minimalist one you can get, with only one pawn for each player:

8/8/8/3pK3/2kP4/8/8/8 w - - 0 1

This pattern can be translated to 30 different positions, with the black pawn on any square in the b7-g7-g3-b3 rectangle. Whoever is on move will lose.

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