Author: Tord Romstad
Date: 04:36:57 04/14/04
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On April 14, 2004 at 06:40:00, Fabien Letouzey wrote: > >>It's really simple. I store more information in the moves than most people. >>Most of you, I guess, store only the from and to squares, and the promotion >>piece in the case of pawn promotions. I also store the moving piece, the >>captured piece, and whether the move was an en passant capture. This gives >>me everything I need to update the hash key, without looking at the board >>at all. The price is that I need a bigger number of bits to store moves >>in the transposition table. > >>Tord > >What about the castling rights? > >E.g. white plays Ra1a7, or black captures a white rook at h1. As far as I can see, this shouldn't cause any problems. When I store the moving and captured pieces in the moves, it is easy to update the castling rights in hash_make_move(), without checking the board position or moving any pieces on the internal board. At the moment, however, I simply don't hash castling rights or en passant information. For this reason (as you know), my PVs will occasionally contain illegal moves. Perhaps I should fix this problem, but that would have the unfortunate consequence of making my old opening book file unreadable. I don't want to force my users to download the big opening book again, or to have a separate hash key used only for opening book probing. Tord
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