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MatPlus.Net Forum General Suicide defense
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(1) Posted by Hauke Reddmann [Wednesday, Feb 19, 2020 12:11]

Suicide defense

This is a spawn-off from a recent thread.

The most natural (ha :-) setting would be a
position "White to win" with a posteriori legalization
of castling. So assume you have a position where Black
could defend by stealing the move right, but to justify
this he has to castle in the following game
(which retroanalytically proves he had the move,
by some retro kludge).
Since he must actually play the move by AP rules,
White can defend by selfmate (or any other thingie
that ends the game).

Has this defense ever been shown?
Has it (White or Black playing for selfmate or -stalemate
to end a game prematurely, when the stipulation is
"reach a field" or any other non-outcome-related one)
ever been done elsewhere?

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(2) Posted by Siegfried Hornecker [Thursday, Feb 20, 2020 07:28]

There is a famous endgame study by Gerd Rinder where White is stalemated in the initial position. The try is an en passant capture. It won a 1st prize or special prize in the Schwalbe many years ago (probably in the retro section?).
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(3) Posted by Hauke Reddmann [Thursday, Feb 20, 2020 09:18]

I know that one (see P0000758). It fulfils *half*
of my idea - Black is stuck after Rc8. But the
fact that Ra7 mates White is not "zweckrein" -
even if, say, White could play Kb6, he can ruin
Blacks O-O-O on the next non-checking move.

Again, see the discussion about AP logic in the
comments: may White *actively* ruin O-O-O?
I.e. does the mere fact that there is a line
containing O-O-O, e.g. after a7 instead of Kb7,
forces White to play this line?

(Read Only)pid=18779
(4) Posted by Joost de Heer [Thursday, Feb 20, 2020 09:18]

Not exactly what you described, but something like this: #8068
(Read Only)pid=18780

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MatPlus.Net Forum General Suicide defense