Computer Chess Club Archives




Subject: Re: Question about evaluation and branch factor

Author: Uri Blass

Date: 10:18:55 11/20/03

Go up one level in this thread

On November 20, 2003 at 12:47:41, Anthony Cozzie wrote:

>On November 20, 2003 at 12:28:57, Marcus Prewarski wrote:
>>I've been completely rewriting the evaluation function of my engine
>>DrunkenMaster (not a strong one) because I was tired of seeing it make some
>>really ugly moves and I want to give it better knowledge of king safety and pins
>>and better passed pawn evals.  When I watch it play 5 minute games against an
>>earlier version it seems like the evaulation is better overall.  However it
>>seems like these evaluation changes have made the branch factor a bit worse in
>>several test postions I have.  And it performs worse in WAC test suites which
>>seems to agree with my observations.  I would think that improving my evaluation
>>function would improve the search branch factor if anything.  So my question is
>>does this mean that my newer evaluation function is actually worse in most cases
>>than my old one or could it be something else like my move ordering is bad to
>>begin with?
>> -Marcus
>More eval -> fewer '=' beta cutoffs.  Its just a fact of life :(  IIRC, Tim
>Foden posted some numbers where material-only GLC outsearched normal GLC by ~4
>ply.  Of course, it lost all its games.

I do not agree.

Maybe if you compare only material with something more complex you are right but
I see no reason for it to be the case with piece square table relative to more
complex evaluation.

More evaluation does not mean that you are slower in test suites and it means
that you often solve the test faster because the evaluation can tell you that
the move is good move even when you do not see that it wins material.


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