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Subject: Re: likelihood instead of pawnunits? + chess knowledge

Author: Maurizio De Leo

Date: 03:12:33 10/26/02

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>I don't follow this with the tre scores, why would you need three?
>The game has a only three posible outcomes, white wins +1, white draws 0, white
>loses -1. That is a closed interval [-1;1] and you can transform that to [0;1]
>without problems if you want.
>
>If you go by the first interval -0.97 would be like -7.34 pawns and 0 would be 0
>and +0.56 might be like +2.3 pawns. There is probably a nice (but slow)
>trigonometric fit to this transformation.
>
>I think the point is it doesn't change anything in the alpha-beta algorithm as
>long as the transformation is injective on the domain (a!=b => T(a)!=T(b)),
>otherwise things would get real spooky.

I think what he wanred to say is that with a single value two different
situation can be evaluated in the same way.
A dead draw and a wild tactical fight where someone will win but we don't know
who are both around 0 pawn units.
With 3 values it would be different, as Uri already pointed out. For example
(5 90 5) instead of (40 20 40)
Maybe the engine could try to go for the draw or for the risky win depending on
some other consideration. However I don't think this is compatible with a
standard min/max algorithm.

Maurizio



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