Author: Dieter Buerssner
Date: 13:11:48 04/04/03
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On April 04, 2003 at 15:06:37, Russell Reagan wrote: >As far as an example, try this: > > rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1 > >The en passant square is e3. Only for the FEN Standard, the ep square must be e3 here. A very doubious rule (I think it is wrong) in that Standard. For the search of an engine (for example for hashing), there is no need to set/hash the ep square, when the pawn cannot be captured. And then your problem is gone ... One might still argue, that in the few real ep-cases, hash could even help when you ignore ep. Perhaps - I don't think, it don't think you could gain much. BTW. Setting the ep target and hashing it always yields in bugs in one typical method of repetition detection (comparing with previous hash signatures): When the position is on the board the second time, you won't see it ... Not hashing ep target could yield in similar bugs. Setting ep target only when a ep capture is possible will solve those problems. However, one subtle problem could remain: it seems that the pawn can be captured ep, but it really cant't be captured because the capturing pawn is pinned to the king. This might be rather expensive to detect in the inner loops of the search. Regards, Dieter
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