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Subject: Local optima / genetic algorithms

Author: James Long

Date: 13:57:04 08/03/98


As I rewrite my program, I've been seriously considering
trying a genetic algorithm to train the evaluation
function.  I've got a pretty good grasp on how to
handle this, but a couple of things are still
bothering me:

Most programmers hand tune their eval functions, either
themselves or with the help of a strong player.  Is
this because the results are generally better, or
because a good learning eval is difficult to write?
Dr. Hyatt - do you think Crafty may be in a state
of local optima?  (Or do you use a learning eval?)
Bruce?  Anybody? :-)  I'm wondering how many
programs get caught up on this.

For the program to "learn," the eval variables must
mutate dependent on the outcome of a game.  One approach
I read about is to set up a tournament of 100 "players,"
each player having random values assigned to its
eval terms (with the exception of the pawn score).
When one player finally wins, the weakest player's
terms are modified.  This requires thousands of games,
but I'm in no hurry.  My question is - how to go about
modifying the eval terms.  I've got a couple ideas,
but I'd like to read more.  Anybody got some good
pointers??


---
James



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