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MatPlus.Net Forum Endgame studies Gerd Rinder, Die Schwalbe, June 1973, 1st prize

### Gerd Rinder, Die Schwalbe, June 1973, 1st prize

The German composer Gerd Rinder is celebrating his 75th birthday today.

I'd like to use this occasion to show the following masterpiece of him.

(= 7+11 )

Gerd Rinder
Die Schwalbe, June 1973, 1st prize (retro section)
White to move and draw

If black still can castle, his last move must have been b7-b5. However, to prove this, he has to castle (A Posteriori condition). So: 1.cxb6 e.p. axb6+ 2.Kxb6 a1R! (2...a1Q? 3.Kb7 Qxa6 mate obviously doesn't prove b7-b5 as the last move) 3.Kb7 R1xa6 4.Rc8! and white has prevented black from castling. So black can't prove the last move is b7-b5 and therefor is already stalemated in the initial position!

Phantastic!

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This actually reminds me of the famous Kofman problem (White retracts a move and mates in 3) where white retracts 1.O-O-O, only to play 1.O-O-O!! in a position with mutually exclusive white and black castling. The argumentation: The retraction of 1.O-O-O doesn't prove that black can't castle, so white has to actually play 1.O-O-O and not 1.Rd1. Today, however, Kofman's problem is incorrect since this view hasn't prevailed (a correction was offered that turns it into a normal threemover but doesn't preserve Kofman's idea).