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Subject: Re: pawn race position

Author: Robert Hyatt

Date: 22:11:20 06/05/02

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On June 05, 2002 at 21:59:19, Jon Dart wrote:

>I used Crafty 18.10:
>
>
>Crafty v18.10
>
>White(1): Black(1): end-game phase
>              clearing hash tables
>note: scores are for the white side
>material evaluation.................  -2.00
>development.........................   0.00
>pawn evaluation.....................   1.78
>passed pawn evaluation..............   0.00
>passed pawn race evaluation.........  -5.90
>king safety evaluation..............   0.00
>interactive piece evaluation........   5.30
>total evaluation....................  -0.82
>
>Note that the overall score is -0.82 (advantage to Black).
>
>I guess I scanned the eval terms a little too fast and came to the wrong
>conclusion.
>
>Weirdly, the "passed pawn evaluation" is way biased toward Black, but the
>"interactive piece evaluation" (which basically means miscellaneous eval terms)
>largely cancels it out. I don't know where the +5.3 comes from.
>
>Still, this version seems to be doing better than later versions, and the
>overall evaluation at least has White close to even.
>
>--Jon


There is a bug.  The "real evaluation" gets -.82..  the "score" command
is not quite right.  The PassedPawnRace() code incorrectly thinks that
white can stop the black pawn because the black pawn needs 6 moves to
promote (5 pawn moves plus one for the king to get out of the way).  This
is wrong.

I am working on a fix so that it will _really_ know this is won, but there
are so many exceptions with the two pawns vs the bishop... ie move the
white king up a couple of squares and the black f-pawn can block the diagonal
so that the h-pawn can promote first...

ugly stuff to compute statically...



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