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Subject: Re: Practical Tablebases (much smaller) ?

Author: Robert Hyatt

Date: 10:23:12 11/13/01

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On November 13, 2001 at 12:03:31, Uri Blass wrote:

>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.
>
>There is a solution for it.
>You probe the tablebases only when the right side is to move.
>
>I understand that calculating the moves when you are in a tablebases position
>becomes more comlicated but it can be solved by 2 ply search.
>
>Uri


This implies you _only_ stop the search when a specific side is on move.
This will break the basic idea of minimax to a degree, because some positions
will be searched one ply deeper than they should be, and that means comparing
apples and oranges in the evaluations those two searches return.



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