Author: Robert Hyatt
Date: 16:59:38 11/21/02
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On November 21, 2002 at 17:58:43, Ingo Lindam wrote: >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 For the one pawn vs one pawn case, I'd bet that I could find one example of each possible position quite easily in a large game collection. Those positions are not that oddball, IMHO... Add 2 more pawns and we are beyond 64 K _possible_ positions... Of course all are not likely in the same search from the same root position... But big trees should blow 64K out quickly. I'll try it later since I can do that easily...
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