Author: Gerd Isenberg
Date: 14:18:34 08/01/03
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On August 01, 2003 at 17:07:07, Omid David Tabibi wrote: >On August 01, 2003 at 16:49:10, Gerd Isenberg wrote: > >>On August 01, 2003 at 16:01:51, Joshua Lee wrote: >> >>>Would someone please explain pawn hash and how much of the whole hash tables it >>>is when you set them to lets say 256MB? >> >>Hi Joshua, >> >>as Rick already mentioned, pawn hash tables are for pure pawn related eval >>stuff. It requires a separate pawn hashkey, incrementally updated if pawn >>formation changes, similar to main hash table. >> >>The size depends on the size of your entries and the number of entries of >>course. The number of entries should be much more less than in main hash table, >>64K entries are quite enough IMHO. But the entry size may be bigger than in main >>hash, depending on what you store (some aggregated eval score or several >>bitbooards with some important properties). >> >>If i think about my eval with a lot of pawn-king or piece interactions... >>May be i throw out pawn hash table in future IsiChess. A lot of pawn patterns >>like, isolated, backward, double, triple, candidates, passers, outside passers, >>duos, rams etc. may be generated on the fly with bitboards and stored a while. >> >>On the other hand, if you hash pawn eval, you may do a lot of really expensive >>things with pawns - > >>the hit rate is about 99%. > >That's about the hit rate I get in closed positions, but for example searching >from the start position, I only get a hit rate of of slightly over 90%. You are right, Omid. Starting position seems really be a worst case for pawn hash hit rate. After 1.e4 e5 it becomes better, but even less 99%. Gerd > > >> >>Regards, >>Gerd >> >>> >>>Thankyou
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