Author: Robert Hyatt
Date: 13:24:25 10/25/99
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On October 25, 1999 at 14:59:21, William Bryant wrote: >Since pawn evaluations are static, ie this pawn formation gives this score, >the amount of information stored in a pawn hash table should be really simple. > >I was thinking of using a simple long long value. > >This gives 64 bits. >Index the bottom 19 bits (that indexes 262144 positions for a table size of > 2M)into the table >Store the hash signature (64 bits) minus the bottom 16 bits for the score. >Between the index and stored score that gives an overlap of 3 bits. > >This should prevent matching errors and keep the record size low. > >Is there any information I'll need that I'm leaving out. > >Thanks in advance. > >William >wbryant@ix.netcom.com I am doing a pure 32 bit hash signature for the pawn hash table. There are not nearly so many different pawn positions as there are chess positions. I ran a lot of tests a couple of years ago, using the 32 bit hash signature, but storing a different 64 bit hash signature for validation... I didn't get any mismatches after playing for several days on ICC with this turned on. I then went to the pure 32 bit hash signature completely... I still use 64 bits for normal hashing of course..
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