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Subject: Re: Crafty bug? (18.12)

Author: Rafael Andrist

Date: 07:47:50 10/18/01

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On October 18, 2001 at 08:51:56, Robert Hyatt wrote:

>On October 17, 2001 at 17:49:39, Robert Hyatt wrote:
>
>>On October 17, 2001 at 13:05:35, Roy Eassa wrote:
>>
>>>On October 17, 2001 at 13:02:34, Robert Hyatt wrote:
>>>
>>>>On October 17, 2001 at 11:15:12, Robert Hyatt wrote:
>>>>
>>>>>definitely a bug of some sort...
>>>>
>>>>A pretty simple bug in fact.  I just fixed it in the 18.12 source and
>>>>re-copied the source to the ftp machine.  If you want to try the fix,
>>>>feel free.  There was a bad calculation that failed when the king was within
>>>>one square of the rook-file promotion square, and the pawn was within one square
>>>>of the promotion square, and the pawn was to move first...
>>>
>>>
>>>Was the bug only in 18.12, or was it also in previous versions?
>>
>>
>>Been there a while...  Nothing has been changed here for several versions.  I
>>am completely rewriting the EvaluateDraws() code and have changed the name to
>>EvaluateWinner().  It returns a bitmask of two bits, 01 means white can win
>>only, 10 means black can win only, 11 means either can win, and 00 means dead
>>drawn.
>>
>>It also recognizes a few more cases.  I temporarily deleted the 18.12 source
>>as I want to fix this completely as part of the final 18.12 release.  I hope to
>>finish it tonight...
>
>
>New version is now available.  It at least handles the test position for this
>thread correctly.  The search is more "stable" in the endgame as well, now.

Did you include this KBP-KP case or did you only fix the bug in the evaluation
of KBP-K endgames? Do you also handle cases, where the defending king is near
enough, but can be forced to go away? E.g.

[D]5k2/8/3K3P/8/8/8/2B5/8 w - - 0 1

regards
Rafael B. Andrist



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