Author: Jay Scott
Date: 13:54:55 02/25/98
Go up one level in this thread
On February 25, 1998 at 05:09:41, Amir Ban wrote: >We all know what the BEST evaluation is. It's the one coming out of >perfect knowledge of the game. But what is good evaluation ? More >precisely, given two evaluation functions, how do you decide which is >better ? The question "which one is better?" is meaningless by itself. Better for what? Label the set of all chess positions with the positions' game- theoretic values, win=1 loss=0.5 draw=0. One thing you might like your evaluation function to do is minimize, say, mean squared error. You might like a good statistical fit to the truth, in other words. But it's easy to construct an evaluation which has an excellent statistical fit yet plays bad chess. For example, imagine an evaluator which is perfect except that it thinks that white is winning after 1. g4 e5 2. f4. The mean squared error is negligible, since only a few positions are wrong, but a program that relies on it is going to lose a lot of Fool's Mates. A program could also play perfectly with an evaluation which had a poor statistical fit. All that's necessary is for one of the optimal moves to be evaluated highest in any position that the program can reach with optimal play up to that point. Jay
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.