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Subject: Re: Winning Chances vs Material/Positional Evaluation

Author: Robert Hyatt

Date: 06:29:32 07/29/99

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On July 29, 1999 at 08:25:58, Chris Carson wrote:

>On July 29, 1999 at 07:16:32, Amir Ban wrote:
>
>>On July 28, 1999 at 18:16:24, Dann Corbit wrote:
>>
>>>On July 28, 1999 at 17:50:51, Kristo Miettinen wrote:
>>>
>>>>The position is the opening array, all pieces in their initial positions. The
>>>>explanation about the eight pawns makes sense, intending to steer Crafty into
>>>>open waters (on the assumption that the opponent is human?)
>>>>
>>>>I was looking into this on a whim, as I use the advantage of White in the
>>>>opening position as my quantum of positional value (on which scale the value of
>>>>a pawn is 6 quanta for me).
>>>Here is the C.A.P. record for that position.
>>>
>>>rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - acd 15; ce -7; pv e4 e6 Nf3
>>>Bb4 Nc3 Ne7 Bc4 Nbc6 O-O O-O d4 Bxc3 bxc3 Na5 Bb5; pm e4; id "C.A.P. 4028";
>>>
>>>I bet you never knew crafty was French.
>>>
>>>Crafty thinks it is behind by 7 one hundredths of a pawn.  This is obviously
>>>conservative because white has a tempo at least.  But I don't think that it is
>>>grossly inaccurate.
>>
>>A correct evaluation is one that matches the winning percentages of the
>>position. I think white has about 54% in serious play, and if so the evaluation
>>should be about +0.20.
>>
>>Amir
>
>Amir,
>
>Interesting point.  If I read you correctly, the "Evaluation" should match
>the winning changes.  This is not the way most programs "Evaluate" a position.
>Granted that a higher "Eval" by a program should mean a higher "Chance" to
>win, it is normally not a "Percentage" based on results.
>
>I have thought that this might be a better method of "Evaluation", some
>programs do use a "Percentage" (Crafty) for opening book moves, but not
>for middle game or end game positions.
>
>Any thoughts on how to incorporate "Percentage" into the "Evaluate" function
>of a program (knowledge)?  Perhaps a "Percentage" "Evaluation" for positions
>and endgames as a part of the learning (Crafty might be able to do this)
>would be useful.  Any comments?
>
>Best Regards,
>Chris Carson


I disagree.  Evaluations are not 'absolute' any more than FIDE Elo ratings are
absolute.  The correct evaluation is the one that lets you _win_ 54% (or better)
of the games from the opening position.  Whether the starting score is +1.00 or
-1.00 is immaterial so long as you choose the best move(s) by using those
scores...



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