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Subject: Winning Chances vs Material/Positional Evaluation

Author: Chris Carson

Date: 05:25:58 07/29/99

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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



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