Author: James B. Shearer
Date: 21:08:53 05/25/98
I was playing a crafty clone on ICC a few days ago. It lost after
declining to take a pawn for no apparent reason. I was curious and
looked at the position after the game. Crafty 14.10 grabs the pawn. I
downloaded crafty 15.7 and it was reluctant to take the pawn. This is
not surprising because the score command gives a lower evaluation for
white (crafty) when the black pawn in question is removed. The pawn may
be weak but it certainly doesn't have negative value. Looks like a bug
of some sort to me.
This is the position.
Crafty v15.7
hash table memory = 12M bytes.
pawn hash table memory = 1.3M bytes.
pondering disabled.
book learning disabled
result learning disabled
position learning disabled
noise level set to 0.
White(1): in all39
White(1): setboard 3r3k/7p/p7/8/2Bp1P2/4r1P1/P6P/3R2K1 w - - 0 39
+---+---+---+---+---+---+---+---+
8 | | | | *R| | | | *K|
+---+---+---+---+---+---+---+---+
7 | | | | | | | | *P|
+---+---+---+---+---+---+---+---+
6 | *P| | | | | | | |
+---+---+---+---+---+---+---+---+
5 | | | | | | | | |
+---+---+---+---+---+---+---+---+
4 | | | B | *P| | P | | |
+---+---+---+---+---+---+---+---+
3 | | | | | *R| | P | |
+---+---+---+---+---+---+---+---+
2 | P | | | | | | | P |
+---+---+---+---+---+---+---+---+
1 | | | | R | | | K | |
+---+---+---+---+---+---+---+---+
a b c d e f g h
White(1): exit
White(1): score
end-game phase
clearing hash tables
note: scores are for the white side
material evaluation................. -0.70
development......................... 0.00
pawn evaluation..................... 0.15
passed pawn evaluation.............. -0.09
passed pawn race evaluation......... 0.00
interactive piece evaluation........ 0.46
total evaluation.................... -0.18
Now remove the black a pawn and white's score goes down.
White(1): in all39a
White(1): setboard 3r3k/7p/8/8/2Bp1P2/4r1P1/P6P/3R2K1 w - - 0 39
+---+---+---+---+---+---+---+---+
8 | | | | *R| | | | *K|
+---+---+---+---+---+---+---+---+
7 | | | | | | | | *P|
+---+---+---+---+---+---+---+---+
6 | | | | | | | | |
+---+---+---+---+---+---+---+---+
5 | | | | | | | | |
+---+---+---+---+---+---+---+---+
4 | | | B | *P| | P | | |
+---+---+---+---+---+---+---+---+
3 | | | | | *R| | P | |
+---+---+---+---+---+---+---+---+
2 | P | | | | | | | P |
+---+---+---+---+---+---+---+---+
1 | | | | R | | | K | |
+---+---+---+---+---+---+---+---+
a b c d e f g h
White(1): exit
White(1): score
end-game phase
note: scores are for the white side
material evaluation................. 0.30
development......................... 0.00
pawn evaluation..................... 0.04
passed pawn evaluation.............. -0.04
passed pawn race evaluation......... 0.00
interactive piece evaluation........ -0.60
total evaluation.................... -0.30
Take the a pawn with the bishop and white's score goes down even
more.
White(1): in all39b
White(1): setboard 3r3k/7p/B7/8/3p1P2/4r1P1/P6P/3R2K1 b - - 0 39
+---+---+---+---+---+---+---+---+
8 | | | | *R| | | | *K|
+---+---+---+---+---+---+---+---+
7 | | | | | | | | *P|
+---+---+---+---+---+---+---+---+
6 | B | | | | | | | |
+---+---+---+---+---+---+---+---+
5 | | | | | | | | |
+---+---+---+---+---+---+---+---+
4 | | | | *P| | P | | |
+---+---+---+---+---+---+---+---+
3 | | | | | *R| | P | |
+---+---+---+---+---+---+---+---+
2 | P | | | | | | | P |
+---+---+---+---+---+---+---+---+
1 | | | | R | | | K | |
+---+---+---+---+---+---+---+---+
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................. 0.30
development......................... 0.00
pawn evaluation..................... 0.04
passed pawn evaluation.............. -0.04
passed pawn race evaluation......... 0.00
interactive piece evaluation........ -0.82
total evaluation.................... -0.52
Black(1): quit
execution complete.
James B. Shearer
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Last modified: Thu, 15 Apr 21 08:11:13 -0700
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