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Subject: Re: How does Crafty handle draws?

Author: Robert Hyatt

Date: 06:37:22 04/11/00

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On April 11, 2000 at 03:33:46, Jeremiah Penery wrote:

>On April 10, 2000 at 15:54:49, Robert Hyatt wrote:
>
>>On April 10, 2000 at 11:01:43, Colin Frayn wrote:
>>
>>>I was just wondering how Crafty handles draws in its evaluation routine.  I've
>>>been playing several 10 minute blitz games (10 min/side) between Crafty and
>>>ColChess and I managed to win the following two games, though I noticed that
>>>near the end Crafty was often giving the position as drawn to many ply (like 20
>>>or more) as it thought it could draw by repetition when behind.  ColChess plays
>>>along a few times, then realises what's about to happen and plays something
>>>else, whereby Crafty's analysis goes very negative again.
>>>
>>>Surely Crafty must know that ColChess will try to avoid a draw when ahead?
>>>
>>>Also, does Crafty have a contempt setting? I would have resigned both of these
>>>games a lot earlier :)
>>>
>>>Cheers,
>>>Col
>>
>>The only thing that will cause the above is drastic differences in the
>>evaluation.  Crafty thinks that the opponent will either repeat or get a worse
>>position...  so it assumes it will repeat.
>
>I think he means after his program has repeated the position twice already.  In
>this case, Crafty will think it's a draw anyway, then it could play an inferior
>repeating move instead of trying to improve the position.


No.. the latest version(s) don't do this.  I too John's idea of not counting
2-fold repeats as draws in the first 2 plies of searching, so that it won't
do what you suggest.  If the current version (.10 or .11) says draw, it is
_really_ a draw if the draw occurs within 2 plies...



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