Author: Dan Newman
Date: 12:23:14 02/23/99
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On February 23, 1999 at 14:43:29, Larry Griffiths wrote: >On February 23, 1999 at 14:33:03, Larry Griffiths wrote: > >>Dan, >> >>I read your post on hash collisions. I have tried some hamming distance >>code and I see little difference when compared to generating random >>numbers. I have been thinking of writing code that does what you said >>where 64 bits must have 32 bits (or 50%) turned on in each number. I also see >>where there are many references to the 12 pieces times 64 squares = 768 >>hash codes. Pawns only use 48 squares for each side, so 32 squares are unused by pawns. > >Forget my reference to the Bishops. > >>768-48 leaves 720 hashcodes for the piece square table. >>Food for thought? Errors in my thinking? >> >>Larry. That's interesting. You can generate a smaller set of random numbers and fill out only those portions of the table that are actually used. And a smaller set can be better optimized in the same period of time. (Currently, IIRC, I use 1024 numbers for the piece-square part since I use Bob Hyatt's numbering scheme for pieces: P=1,N=2,K=3,B=5,R=6,Q=7 -- which is quite nice for distiguishing sliders from non-sliders.) -Dan. -Dan.
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