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Subject: Re: Tablebases question (newbie here)

Author: Sanjiv Karnataki

Date: 01:48:12 12/28/99

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Bruce:

Thank you for the answer. Do you by any chance know where I can find more
information on this subject? particularly the generation/format of tablebase
files (nalimov).

thanks again.

On December 28, 1999 at 04:22:39, Bruce Moreland wrote:

>On December 28, 1999 at 01:49:09, Sanjiv Karnataki wrote:
>
>>Hi All,
>>
>>I have read about tablebases and I like the way Crafty (Crafty rules !) uses
>>them to play perfect endgames for 3/4/5 pieces. I wanted to know a bit more
>>about them, how they are generated and the format of the tablebase files but
>>cannot find any article (first time yahoo, and altavista have failed me). The
>>only link i have found seems to be defunct. (chess.onenet.net, SJE's
>>tablebases).
>>
>>Thanks in advance
>
>They are generated by working backwards from known positions.  Every conceivable
>position is examined, and those where one side is checkmated are marked as mates
>in zero.  Then every position is examined again, to see if the side to move can
>reach a mate in zero position, and those are marked as mates in one.  Then every
>position is examined again, to see if it is impossible to avoid moving to a mate
>in one position.  Then every position is examined again, to see if it is
>possible to reach one of the positions from which it is impossible to avoid a
>mate in one, these are mates in two.  This is done repeatedly until it's
>impossible to create any deeper mates, at which point everything left over is
>determined to be a draw.
>
>I have oversimplified but essentially this is what happens.
>
>bruce



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