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Subject: Re: Practical Tablebases (much smaller) ?

Author: Sergei Smith

Date: 07:32:23 11/13/01

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On November 13, 2001 at 10:09:30, Robert Hyatt 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".
>
>How would you handle all the common zugzwang positions?  black king at e6,
>white king at e4, white pawn at e3.  White to move draws.  Black to move
>loses.
>
>
>> Surely there is a reasonable simplification in that regard
>>based on symmetry. Promotion of a pawn to less than a Queen is rare and could be
>>disregarded.
>
>There are plenty of positions where underpromotion is the only way to avoid a
>stalemate.  That would convert many wins into draws.
>
>
>
>> Perhaps castling can be disregarded because it seldom happens in
>>the endgame.
>
>castling is already ignored and not part of the tables.
>
>
>> 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. That would also make it more practical to generate 6-piece
>>positions. Anybody know how?
>>WP
>
>
>eliminating 1/2 the tables cuts it to 3.75 gigs.  None of the other changes
>you suggest are doable.  And eliminating either wtm or btm will cause problems
>as I mentioned.
>
>7.5 gigs is a trivial amount of disk space today, with new machines usually
>coming with at least a 60 gig drive.

Do you think it will ever be possible in the distant future to have tablebases
with 7 pieces , 8 pieces , ... ?



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