Author: Pham Hong Nguyen
Date: 07:54:08 07/03/04
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On July 03, 2004 at 01:51:57, Dan Honeycutt wrote: >On July 03, 2004 at 01:19:25, Tor Lattimore wrote: > >>Thanks! >>Another thing also to do with pawn hash. What do you store in it? i've heard of >>some putting the king in. Pawn hash is only used for evaluation, so no need for >>bounds ec cetera either is there? unless I mis-understand the idea, only >>evaluation scores are needed (and key of course). I think paswnhash may save information which is useful for other pieces such as open files for rooks. You also may need to know where the weak points are to defend/attack. If you distinguish scores of pawn structures by game phases (opening, mid, end) you may compute 3 different scores to save them all (in case you save only scores) instead of saving structures only. >> >>What sort of replacement schemes are typically used? I use always replace in my >>standard transpos table, not sure if thats best here? > >Hi Tor. >To your original question, pawn hash doesn't have to be too big. Tord Romstad >may jump in and say a few hundred entrys are sufficient, but for most of us it's >at least a few thousand. > >I used to hash the king, but after a fair amount of twiddling I threw him out. >Others suggested to me a dual hash, pawns only and pawns + king. Haven't tried >that. > >Replace always or clear the table on any pawn move. You'll rebuild it after a >search or two. I don't use pawn hash, but I see that suggestion is quite strange for me. Why do you "clear the table on any pawn move"? Any proof by data? I think the pawn hash contains only tiny information dealing with the latest pawn move, but the larger part contains information of deeper pawn structures on the search. Clearing means you lose this useful information. Pham > >Dan H.
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