# Computer Chess Club Archives

## Messages

### Subject: Re: Static evaluation after sac, how about asymmetry?

Author: Dan Homan

Date: 08:49:42 12/04/99

Go up one level in this thread

```On December 03, 1999 at 21:31:09, Vincent Diepeveen wrote:

>On December 03, 1999 at 18:10:03, Will Singleton wrote:
>
>>On December 03, 1999 at 08:49:19, Andrew Williams wrote:
>>
>>>Over the last few days, I have been fascinated by the discussions on CCC
>>>about positional sacrifices. Some of the discussion has centred on the value
>>>assigned to the attack that is obtained after the sacrifice and I was wondering
>>>how other programs evaluated the position after Hossa's sac:
>>>
>>>r3q1k1/ppp1rp2/2n1b2Q/8/2P5/3B4/PPP2RPP/5RK1 b - - 0 2
>>>
>>>This is after 1. Bxh6 gxh6 2. Qxh6 from the original position posted by
>>>Peter McKenzie. PostModernist's static evaluation of the position is presented
>>>below. Essentially, it thinks that White is winning by 0.71. The ATTACKTOTAL
>>>score is generated by analyzing the squares around the King to see how many of
>>>them are attacked and what sorts of pieces are attacking them. Please note that
>>>not all the factors that contribute to PM's score are included in the output
>>>below.
>>>
>>>Could other programmers post similar information? I believe that even an
>>>overall static evaluation would be interesting.
>>>
>>>Cheers
>>>
>>>Andrew Williams
>>>
>>>
>>>
>>>SCORE ANALYSIS
>>>BLACK to move
>>>
>>>MATERIAL -137 (Positive means WHITE has more material) W:19086 B:19223
>>>Game stage M
>>>Actual moves played: 1 (halfMoves=1)
>>>
>>>Fifty move counter: 0
>>>
>>>r=547      #       #       #    q=1040     #    k=15939    #
>>>
>>>o=103   o=106   o=103      #    r=565   o=94       #       #
>>>
>>>   #       #    n=346      #    b=346      #       #    Q=1022
>>>
>>>   #       #       #       #       #       #       #       #
>>>
>>>   #       #    P=101      #       #       #       #       #
>>>
>>>   #       #       #    B=344      #       #       #       #
>>>
>>>P=103   P=103   P=98       #       #    R=553   P=103   P=115
>>>
>>>   #       #       #       #       #    R=555   K=15993    #
>>>
>>>
>>>HCW=1   HCB=1
>>>cannotCW=1      cannotCB=1
>>>CCRW=0  CCRB=0
>>>
>>>Piece Bonuses White=4   Piece Bonuses Black=-34
>>>
>>>KINGEXPOSURE WHITE=3    KINGEXPOSURE BLACK=16
>>>DANGERSQUARES WHITE=0   DANGERSQUARES BLACK=5
>>>ATTACKINGFORCE WHITE=21 ATTACKINGFORCE BLACK=0
>>>ATTACKTOTAL WHITE=240   ATTACKTOTAL BLACK=0
>>>
>>>
>>>EVALUATION : 71 (positive means WHITE is winning)
>>
>>For Amateur:
>>
>>r3q1k1/ppp1rp2/2n1b2Q/8/2P5/3B4/PPP2RPP/5RK1 b - -
>>
>>Using a static eval, I get different results if it is White or Black doing the
>>evaluating.  I guess this is a result of my asymmetrical king-safety.
>>
>>White says +0.73, Black says +1.29 (+ is good for white).  Does anyone else do
>>this asymetrically?
>>
>>Will
>
>Except for an experiment giving the side to move a bonus to some extend
>i've never been assymmetric. When I threw out this bonus too, then
>diep improved a lot in level.
>
>Logical one would say a bonus for having the side to move is good,
>but it never worked for DIEP.
>
>Never figured out why. Did i have a bug?

I tried this in EXchess for a while and had the same experience that
you did.  When I took the bonus out, EXchess got better.  I am still
surprised that it doesn't work... oh well.

- Dan

>
>Apart from this discussion, from which i don't know whether it's good to have,
>being assymetric becasue white might be a human and black a computer,
>i am against using an assymmetric evaluation function for that.
>
>Contempt factor should already prevent getting a draw namely. No need
>to underestimate the opponent somehow or favour open position for the
>computer a lot more, though at the icc server this means obviously
>you lose a lot of points to draws in closed positions.

```