Problem 673: Alain Bienabe - Fairy (Back-Home) |
1.f1S Kg1 2.Sg3 Kf2 3.c1B hxg3 4.Bf4 gxf4 5.h2 f5 6.h1R f6 7.Rh3 f7 8.Rh7 f8Q# AUW in miniature (Author)
Back-Home: if a side can move a piece (King included) to the square it occupied in the initial (diagram) position, it must do it, unless a self-check. |
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Comments
In principle, a condition should be used for creating a content, not only for the cook-stopping.
A content relies on the right choice so, 1...Kf2!(hxg3?) and 3.c1B!(c1Q?) present the choice motivated by the condition (or, the condition creates the motivation for the play).
The mandatory 7.Rh1-h3 doesn't seem to create anything. The only legal move is not even a tempo-move.
(But at least, Black can't waste a move by 4.Bb2/g5 g4 5.Bf6 g5 etc., because 8.Rh1-h7 would be illegal.)
It's obvious from the definition that 6.h1Q & 8.Qh7 f8Q+ 9.Qg8! would be legal because the back-home move 9.Qh3 would be a selfcheck.
However, the condition is quite tricky. For instance (if I remember well the explanation by the inventor), 1.f1S Kg1 2.Sg3 hxg3 3.c1Q Kh1! would not only be legal but mandatory, since 3.c1Q attacks only the square c2.
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