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Subject: Re: Ultra small pawn hash efficiency

Author: Ingo Lindam

Date: 14:58:43 11/21/02

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On November 21, 2002 at 15:39:27, Robert Hyatt wrote:

>On November 21, 2002 at 12:39:24, Matthias Gemuh wrote:

>>Some hasty and wrong thinking then, when I implemented my pawn hash.
>>Maybe I somehow excluded strange positions like all pawns on 2nd and 3rd rows.
>>I shall check my code and logic later.
>>I generate keys such that they lie in range 1..2x64kB and use them as index.
>>I hit 95%..99% in middle game and WAC.

>Just one white pawn gives you 48 different positions.
>one white pawn and one black
>pawn gives you 48*48 different positions.  or, rounding down a bit, 48 could be
>replaced by 2^5 (32).  48*48 could be approximated by 2^10 or 1024.  two more
>pawns and we are going to blow past 64K positions.

I don't see a contradiction between the two statements. Aside from there are
just 48*47 possible positions with one white and one black pawn you count a lot
of positions having nothing todo with chess reallity and even more positions
being atleast very unlikely. I can imagine that there are not more than 2x64k
positions covering 95% of the occuring midgame positions.

[D] 8/1ppppppp/7p/8/8/P7/PPPPPPP1/8 w - -

internette Gruesse,
Ingo




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