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Subject: Re: Practical Tablebases (much smaller) ?

Author: Uri Blass

Date: 06:18:02 11/13/01

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On November 13, 2001 at 09:16:09, Uri Blass wrote:

>On November 13, 2001 at 08:31:09, William Penn wrote:
>
>>I suspect this has been discussed before but I didn't pay attention, so please
>>pardon my redundancy. If you could just point me in the right direction, much
>>appreciated...
>>
>>Can't we make some assumptions without compromising very much practical playing
>>strength and significantly reduce the size of the endgame tablebases? For
>>example it seems a waste to generate separate positions for "white to move" and
>>"black to move".
>
>It is also a waste of space to remember the exact number of moves to mate and
>knowing the number of moves divided by 2 is enough and if you know it you can
>calculate the exact number of moves to mate.
>
>
> Surely there is a reasonable simplification in that regard
>>based on symmetry.
>
>Symmetry is used in building the tablebases
>
>
> Promotion of a pawn to less than a Queen is rare and could be
>>disregarded.
>
>This is going to save time in generating the tablebases with pawns but it is not
>going to chnage much the space that is needed for the 3-4-5 piece tablebases.
>
> Perhaps castling can be disregarded because it seldom happens in
>>the endgame.
>
>It is already disregarded.
>
> I suppose we must keep en passant(?). I'm guessing that the size
>>could be reduced to perhaps only 1GB for all of the 3-4-5 piece positions vs the
>>current 7GB.
>
>Part of the 7GB is for generating unimportant tablebases of a king and three
>pieces against a king when there is no position with king and 3 pieces against
>king when programs cannot win.
>
>Uri

I mean no KXXX vs K position that is not drawn that programs cannot win(of
course there are stalemate positions).

Uri



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