Author: Tony Werten
Date: 01:21:25 03/08/03
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On March 08, 2003 at 03:43:20, Ed Schröder wrote: >On March 08, 2003 at 01:42:15, Robert Hyatt wrote: > >>On March 08, 2003 at 01:29:46, Joel wrote: >> >>>Hey All, >>> >>>Just wondering what everyone thinks is the best way to implement a pawn hash >>>table? >>> >>>At the moment I am incrementally generating a seperate pair of pawn hash keys, >>>and using them to index a table - very similar to how my transposition table >>>works. >>> >>>Is it possible to do _significantly_ better than this? It seems to be somewhat >>>expensive to do, although having said that my NPS still went up at least 20% in >>>most situations. > >>That is what everyone since chess 4.x has done. Two signatures, one for >>all pieces and pawns, one just for pawns. > >I don't use it, the problem is that you can not evaluate the coherence between >pawns and the other pieces. If you have stuff like that in your eval pawn >hashing is unusable and IMO that evaluation (coherence) is a must in a chess >program. One doesn't exclude the other. You can skip expensive "is this a backward/passed/ouside passed/isolated/double pawn" tests if the hashtable indicated that there isn't a backward/passed etc pawn on the file the pawn is on. If there is and there isn't a double pawn on the current file then you can skip all tests because you know it can only be the current pawn. Tony > >My best, > >Ed > > > >> >> >>> >>>I am not really worried about effeciency as much as some other people here, so I >>>guess I am really asking whether I am missing something major. >> >>Doesn't sound like it. But you will end up storing more than just a score for >>the position. IE passed pawn locations, weak pawn locations (or bitmaps that >>feature them). Etc... >> >>> >>>Regards, >>>Joel
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