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Subject: Re: How does Crafty handle draws?

Author: Robert Hyatt

Date: 17:20:35 04/10/00

Go up one level in this thread


On April 10, 2000 at 17:31:57, Pete Galati 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.
>>
>>to make it resign sooner, try "resign=3" which resigns 5 moves after getting
>>to be a piece down.
>>
>
>I assume that that's actually somewhat flexible, I mean if you set Crafty to
>resign at 3 (3 pawns?) then Crafty goes down to scores of -3 or less in the
>search (must be the final search depth that Crafty reaches before making it's
>move) that if at the 4th move, if Crafty has somehow climbed out of the whole
>enough to interpret it's score as being -1, then the resign is off.  In other
>words, 5 consecutive searches at -3 would get Crafty to resign.
>
>Or, does Crafty score each position currently on the board and resign by that (5
>consecutive positions below resign number) but that method would have to take
>away Crafty's ability to be able to see if it would have a way to dig it's way
>out of a bad spot.
>
>Pete


This is based on the real game.  IE if five consecutive moves are played by
crafty, and the score is < -3 for each move (final search value for each
move) then it will resign after playing the 5th move.



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