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Subject: Re: Endgame tablebases and draw by repetition : a bug in Crafty 16.5T (Fritz

Author: Sylvain Renard

Date: 12:21:18 07/12/99

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On July 12, 1999 at 10:16:11, Robert Hyatt wrote:

>On July 12, 1999 at 03:46:02, Sylvain Renard wrote:
>
>>Using Crafty 16.5T (Fritz interface) with endgame tablebases,
>>I have noticed this bug (easy for me, my program has the same!!) :
>>
>>Start position:
>>
>>4k3/8/6P1/4K1P1/8/8/8/8 w - - 0 1
>>
>>White: Ke5, pawns g5 & g6
>>Black: Ke8
>>white to move (machine = black, white = weak player!).
>>1.Kd6?? (there are several wining moves!) 1...Kf8= 2.Ke5 Ke8?? leading
>>to the start position, so Crafty 16.5T (Fritz interface) evaluation is 0.00 ,
>>because of the repetition of the position!
>>  This bug is not present in "normal" Crafty 16.11 (Winboard interface) so I
>>wanted to ask Mr Hyatt his explanation.
>>  Thank you and best regards,
>>    Sylvain Renard
>
>
>There doesn't appear to be anything wrong.  Crafty considers two repetitions a
>draw, as it always has.  In that regard, the above is a draw as far as it is
>concerned.

   A program should never play a losing move in this position!
Now the opponent can play 3.Ke6, 3.Kf5 or even 3.g7 and win.
I still consider that this is a bug!






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