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Subject: Re: Pawn Transposition Table

Author: Robert Hyatt

Date: 10:48:02 01/12/98

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On January 12, 1998 at 10:49:20, Stuart Cracraft wrote:

>The 93% table-probe match I mentioned before for pawn transposition
>table was for discrete, unrelated positions, such as from a problem
>suite.
>
>When the pawn tranposition table is not cleared between moves in
>a regular game, I am getting typically 95-99%.
>
>I'm pretty sure of my hash function, however I'll try some other
>things. Formerly, I just took a mask of the bits for the index into
>the hash table. Recently I've done a modulo of the hash to determine
>the index.
>
>--Stuart
>

Here's a good sanity check.  I ran win at chess #141 for 45 seconds.
I hashed 99% of the pawn scores.  The raw numbers were 4,341,832 probes
attempted, 4,327,288 probes successful.  IE Crafty only evaluated some
15,000 pawn positions out of 4.3 million calls to evaluate pawns.  This
number was similar for every position in WAC (plus others) that I
tested.

note your hash (pawns) has to be large enough to hold everything,
otherwise
it is not as effective.



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