Author: Robert Hyatt
Date: 07:15:37 02/03/99
Go up one level in this thread
On February 02, 1999 at 00:24:59, James B. Shearer wrote:
>On January 31, 1999 at 10:43:10, Robert Hyatt wrote:
>
> <snip>
>>
>>No idea why it takes 16 plies however... but I'll look...
>>
>
> A big part of the reason is crafty 16.3 is far too optimistic about g5.
>This can lead to the positions like that shown below which crafty scores -2.35.
>This is quite optimistic considering that material is even and the position is a
>dead draw. Crafty 15.15 scores this position -1.19 (see below) which is still
>optimistic but better.
>
I agree with the evaluation, in that if anybody wins, black wins. The
protected passed pawn completely limits white's king to a few squares.
But the fact that black's king is 'locked out' is an issue, which i try to
resolve via search rather than by evaluation. On a normal machine, it can
get to 16 plies very quickly and discover that it can force entry by pushing
the other pawn... but it needs the depth to 'see' this rather than trying
to 'evaluate' this...
James B. Shearer
>Crafty v16.3
>
>White(1): in fit40a
>White(1): setboard 8/8/4p1k1/1p1pP1p1/p2Pp1P1/P1P5/1P2K3/8 b - - 0 40
>
> +---+---+---+---+---+---+---+---+
> 8 | | | | | | | | |
> +---+---+---+---+---+---+---+---+
> 7 | | | | | | | | |
> +---+---+---+---+---+---+---+---+
> 6 | | | | | *P| | *K| |
> +---+---+---+---+---+---+---+---+
> 5 | | *P| | *P| P | | *P| |
> +---+---+---+---+---+---+---+---+
> 4 | *P| | | P | *P| | P | |
> +---+---+---+---+---+---+---+---+
> 3 | P | | P | | | | | |
> +---+---+---+---+---+---+---+---+
> 2 | | P | | | K | | | |
> +---+---+---+---+---+---+---+---+
> 1 | | | | | | | | |
> +---+---+---+---+---+---+---+---+
> a b c d e f g h
>
>Black(1): exit
>
>Black(1): display
>Black(1): score
>end-game phase
> clearing hash tables
>note: scores are for the white side
>material evaluation................. 0.00
>development......................... 0.00
>pawn evaluation..................... -0.75
>passed pawn evaluation.............. -0.40
>passed pawn race evaluation......... -0.50
>interactive piece evaluation........ -0.70
>total evaluation.................... -2.35
>
>Crafty v15.15
>
>White(1): in fit40a
>White(1): setboard 8/8/4p1k1/1p1pP1p1/p2Pp1P1/P1P5/1P2K3/8 b - - 0 40
>
> +---+---+---+---+---+---+---+---+
> 8 | | | | | | | | |
> +---+---+---+---+---+---+---+---+
> 7 | | | | | | | | |
> +---+---+---+---+---+---+---+---+
> 6 | | | | | *P| | *K| |
> +---+---+---+---+---+---+---+---+
> 5 | | *P| | *P| P | | *P| |
> +---+---+---+---+---+---+---+---+
> 4 | *P| | | P | *P| | P | |
> +---+---+---+---+---+---+---+---+
> 3 | P | | P | | | | | |
> +---+---+---+---+---+---+---+---+
> 2 | | P | | | K | | | |
> +---+---+---+---+---+---+---+---+
> 1 | | | | | | | | |
> +---+---+---+---+---+---+---+---+
> a b c d e f g h
>
>Black(1): exit
>
>Black(1): score
>end-game phase
> clearing hash tables
>note: scores are for the white side
>material evaluation................. 0.00
>development......................... 0.00
>pawn evaluation..................... -0.39
>passed pawn evaluation.............. -0.40
>passed pawn race evaluation......... 0.00
>interactive piece evaluation........ -0.40
>total evaluation.................... -1.19
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