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Subject: Re: Crafty bug? (18.12)

Author: Rafael Andrist

Date: 11:23:44 10/18/01

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On October 18, 2001 at 14:20:39, Dann Corbit wrote:

>On October 18, 2001 at 10:47:50, Rafael Andrist wrote:
>
>>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
>
>EPD Kit revision date: 1996.04.21
>unable to open book file [e:\crafty\release/books.bin].
>hash table memory = 192M bytes.
>pawn hash table memory = 80M bytes.
>EGTB cache memory = 32M bytes.
>draw score set to    0.00 pawns.
>choose from book moves randomly (using weights.)
>choose from 5 best moves.
>book learning enabled
>result learning enabled
>position learning enabled
>threshold set to 9 pawns.
>5 piece tablebase files found
>19045kb of RAM used for TB indices and decompression tables
>
>Crafty v18.12
>
>White(1): st 60
>search time set to 60.00.
>White(1): setboard 5k2/8/3K3P/8/8/8/2B5/8 w - -
>1. Bb3 Ke8 2. h7 Kd8 3. h8=Q#
>White(1):

What do you want to say? It's clear that it is very easy using EGTB.

Rafael B. Andrist



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