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Subject: Re: 0x88 vs 144 (or 12x12)

Author: Ricardo Gibert

Date: 04:41:41 10/26/02

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On October 26, 2002 at 03:01:15, Russell Reagan wrote:

>What I mean is, there are (approx) 75,484,103,766,819,471,360,000 different pawn


The positions of all the pawns can be represented by a 48 bit bitmap and their
colors by a 16 bit bitmap for a total of 64 bits. This includes illegal pawn
formations too so your figure is off by at least a factor 4000.


>formations for all pawns on the board, minus some that are duplicates and not
>possible to reach, and then plus all of the 8 black pawns vs. 7 white pawns, 7
>black pawns vs. 8 white pawns, 7 vs 7, 6 vs 7, 7 vs, 6, etc...and then if you
>add in the king like you say, that makes for a lot of positions, and I would
>assume that the pawn hash table is smaller than the normal hash table, so
>there's no way to store information about all of the pawn formations, and you're
>probably going to have more collisions than you do in the normal transposition
>table. It makes me wonder if there are ever errors caused by this. Using
>bitboards, you could just calculate this stuff on the fly and it will always be
>correct.
>
>Russell


No collision errors if the 64 bits are stored in the table.



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