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Subject: levers and pawnhash hit-rate

Author: Gerd Isenberg

Date: 12:57:23 11/15/04

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


[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 - -

Re: levers and pawnhash hit-rate Dieter Buerssner 10:04:45 11/16/04
- Re: levers and pawnhash hit-rate Gerd Isenberg 14:20:39 11/17/04
Re: levers and pawnhash hit-rate Robert Hyatt 08:36:44 11/16/04
- Re: levers and pawnhash hit-rate Gerd Isenberg 13:50:03 11/17/04
Re: levers and pawnhash hit-rate Richard Pijl 00:45:08 11/16/04
Re: levers and pawnhash hit-rate Uri Blass 13:40:47 11/15/04
- Re: levers and pawnhash hit-rate Wayne Lowrance 15:30:02 11/15/04
  - Re: levers and pawnhash hit-rate Dann Corbit 16:10:58 11/15/04

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