Author: Dann Corbit
Date: 19:56:40 01/11/99
Go up one level in this thread
On January 11, 1999 at 20:58:11, Graham Laight wrote: >On January 11, 1999 at 13:57:31, José de Jesús García Ruvalcaba wrote: > >>On January 09, 1999 at 05:55:25, Graham Laight wrote: >> >>>As I was sitting eating my breakfast just now, it occured to me that there are >>>basically 3 items that, between them, will influence how close an evaluation of >>>a chess position is to how good that position really is: >>> >>>1. The number of pieces of knowledge the evaluation function can call upon >>> >>>2. The quality of those pieces of knowledge >>> >>>3. The accuracy of selecting the right pieces of knowledge (and their >>>appropriate weightings) for the position at hand >>> >>> >>>Does anybody have any thoughts about this? >> >>I think that different evaluation functions are not comparable by themselves. > >Why not? > >You take a chess position, and run 2 different evaluation functions against it. > >The one that more accurately scores the position is the better evaluation >function. > >>Overall program strength is. I mean, you can compare two evaluation functions >>once you have all the other components of the programs fixed; but with a >>different set of other components you can get different results. >>Among the "other components" I can see: >>1. Hardware: processor speed, and amount of memory used for hash tables. The same function may perform very differently depending upon CPU, memory available, etc. >>2. The search algorithm, including extensions. The algorithm chosen will have O(f(n)) relevance. So a given algorithm may perform better at short time controls but lose out at long time controls >>3. The opening book. The opening book may be *used* by the evaluation function, especially if it contains more data than just the position. Examples: What is the frequency of win/loss/draw for this position by players of ELO >= x? >>4. Endgame tablebases. These can *definitely* be an integrated part of the evaluation function. If they are not, then they probably should be. >>5. The time control. This comes into relevance if you are talking about a particular algorithm. See remarks on (2) above. >This is like saying, "You cannot evaluate the engine in a car unless you take >into consideration the door handles and the headlights". > >I wanted to discuss the evaluation function of a program on its own - not the >other stuff - important though I agree it is. I think that all of the above can (indeed) be an integral part of the evaluation function. >Ah well - I have to admit that sometimes it's the door handles that sell the >car. > >Graham. > >> I think that the correct "accuracy" of the weightings can dramatically change >>with these factors.
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