Author: GeoffW
Date: 16:07:24 08/06/04
Go up one level in this thread
On August 06, 2004 at 18:33:26, Robert Hyatt wrote:
>On August 06, 2004 at 18:21:51, GeoffW wrote:
>
>>Hi
>>
>>My program has been playing some test games against Dorky and getting soundly
>>beaten, it got me thinking about my eval function which is pretty dumb and badly
>>in need of some chess knowledge !
>>
>>What I noticed in some of the games was that Dorky was seeing threats sometimes
>>10 or 15 plies earlier than my program, as we were searching to similar depths
>>it could only be that Dorky has much better eval function.
>>
>>Here is one of the positions that showed this effect, material is even, but
>>black looks to me to be in a horrible position
>>
>>[D]1b3rk1/4qb1p/2r1pRpP/2ppP1P1/P3pQB1/1PB1P3/8/5RK1 b - - 9 44
>>
>>My program (Black)reckoned that it was only 0.25 of a pawn down, where as Dorky
>>reckoned white was winnning by 2.2.
>>
>>I tried this position with a few programs, only Dorky and Crafty scored white
>>ahead by > 1.5 pawns.
>>
>>Any suggestions as to what the important factors are to evaluate this position
>>as strongly good for white ?
>>My program hasnt really got any mobility scoring, no king tropism and rather
>>basic pawn structure eval. Wondering which area I ought to try first ?
>>
>> Regards Geoff
>
>
>Crafty's static eval here is +1.5 as you mentioned...
>
>The primary points are (a) the f-file is open and occupied by white's three
>major pieces. The pawn at h6 makes g7 another weakness, not to mention being a
>potential passer if the h7 pawn goes away.
>
>Main problem here is king safety, with the white majors pointed right at the
>black king.
Hello Bob
Thanks for the quick reply, I was checking the score with Crafty as you posted
note: scores are for the white side
material evaluation................. 0.00
development......................... 0.00
pawn evaluation..................... -0.13
passed pawn evaluation.............. 0.00
passed pawn race evaluation......... 0.00
king safety evaluation.............. -0.46
interactive piece evaluation........ 1.88
total evaluation.................... 1.29
Black(1):
king safety as listed here is actually good for black, the important factor
though is the large interactive piece evaluation of 1.88
Is this term simply adding up the combined attacks against the enemy king , or
does it look for more subtle factors as well?
I assume Crafty must look at the squares adjacent to the enemy king and also
ignore the defending rook and bishop ?
I guess the position above would have scored highly for this term as I think
Crafty may have a non linear scaling for this type of multi piece attack ?
Incidently, even a strong engine like Gothmog after analysing this position for
30 seconds, still only reckons white is ahead 0.4.
Geoff
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