Author: Robert Hyatt
Date: 08:36:44 11/16/04
Go up one level in this thread
On November 15, 2004 at 15:57:23, Gerd Isenberg wrote: >Hi, > >i use the difference of weighted pawnbitboards ( 5*whitepawnBB - 3*blackpawnBB ) >mod 65077 as an index for a 64K entry pawnhash-table. Most often my pawnhash >hit-rate is quite ok, > 95% or even 99%. But it seems that a lot of pawn levers >decrease my hit-rate due to collisions. > >With "maximum lever" positions my pawnhash hit-rate is only about 75% after a 30 >second search on my amd64 2.2GHz box (~80% without eval hashing). > >I guess a zobrist-key pawn-hashing scheme is better here. >Curious about your pawnhash hit-rates with one of the positions below. > >Btw. how many levers has each position, 8 or 14? > >Thanks, >Gerd > For the first position, I don't consider it to have _any_ levers. I evaluate (personally) levers to be pawn pushes that cause contact with an enemy pawn. These pawns are all in contact already. The idea behind a lever is that it is a _potential_ pawn break that you can play when you are ready... > >[D]8/k7/8/pppppppp/PPPPPPPP/8/8/K7 w - - >[D]8/1k6/8/pppppppp/PPPPPPPP/8/8/1K6 w - - >[D]8/2k5/8/pppppppp/PPPPPPPP/8/8/2K5 w - - >[D]8/3k4/8/pppppppp/PPPPPPPP/8/8/3K4 w - -
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