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Subject: Re: levers and pawnhash hit-rate

Author: Uri Blass

Date: 13:40:47 11/15/04

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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.

I have no pawn hash tables so I have no pawn hash hit rates.
The only pawn information that I calculate and use is passed pawns,isolated
pawns and protected passed pawns and I do not know what is pawn levers.

I do not use hash to store the information because I found that pawn hash does
not change much for me and updating the bitboards incrementally is about the
same speed as storing the information in hash so I decided to go for the simple
solution.

Uri



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