Author: Simon Finn
Date: 09:10:22 11/08/01
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On November 08, 2001 at 08:18:06, guy haworth wrote: > >Nice example. No extant EGT covers castling rights (though Nalimov covers e.p.) >- and the last EGT to so do was apparently by Dekker in the 1980s. > >There are in fact 32 'zones' to an endgame, I think this is an underestimate. > defined by the 2^5 combinations of >the 5 castling/e.p. features, 2 ^ 4 for castling options, I agree with. En-passant requires more than a factor of 2, however. Consider a position with White pawns on a4 and c4, and a Black pawn on b4. Black to move. Then the 3 en-passant options are: (1) No en-passant capture is possible. (2) White's last move was a2-a4. Black can play b4xa3 e.p. (3) White's last move was c2-c4. Black can play b4xc3 e.p. In the worst case, we can have up to 6 en-passant options (I think). > some of these zones being empty if the required Ps >and/or Rs are not available: however, note that KRPKRP features everything >except castling-options on both the K and Q sides. ... and positions where more than one pawn might have made the last (double) move. Simon > >Certainly, there are studies that require O-O-O in the solution: > >A. Selesniev, Tidskrift for Schack, 1921: e1b6 0400.10 3/2 Win ... >wKe1,wRa1,wpd6/bKb6,bRb2 >1. d7 (1. O-O-O? Ra2 2. d7 Ra1+ 3. Kc2 Rxd1 4. Kxd1 Kc7 =; 1. Ra8? Kc6 =) Kc7 2. >d8=Q (2. O-O-O? Rb8 =) Kxd8 3. O-O-O+ > >... remarkably similar to your example. > >G
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