Author: Roy Eassa
Date: 13:04:51 10/08/02
Go up one level in this thread
On October 08, 2002 at 03:30:47, Frederic Louguet wrote: >The first time Chess Wizard played a real game of chess was in 1994. I worked a >lot in 1994/1995/1996, and in 1996 it won the french championship with Chess >Guru. I read a lot of publications, studied some source code (Turbo Chess in >Turbo Pascal, GNU, later Crafty), tried a thousand ideas that did not work, >found a few that really worked... > >I tried the bitboard approach very early (1995) because of the possibilities >regarding evaluation. I always wanted Wizard to have a good evaluation, and a >lot of complex things were easier to implement with bitboards. I learned some >bitboard tricks from Crafty (in the 9.x to 10. versions I think) that I had not >thought about before. But Chess Wizard is not entirely bitboard-based, it's more >a hybrid approach. > >I have two problems : my opening book is not very good, and I don't seem to find >a way to make forward pruning really work. I tried 6723 ideas, a few times I >thought I had found the solution, but everytime it was a false impression. Maybe >I am forward-pruning challenged. I use null move (R=4 very far, then R=3, then >R=2), I recently removed all checks from the quiescence search. The strength of >Chess Wizard is based on two things : good evaluation, and search extensions. I >use many threat extensions with small increments (2/16 of a ply), strange out of >checks extensions, and so on. I tried singular extensions too, but with bad >results. > >When Wizard detects some patterns in the position, it simply tones down, and >sometimes even shuts down completely, entire parts of the evaluation fonction to >concentrate on the parameters that really counts (so other parameters don't get >in the way). > >But I really would like to find super-efficient forward pruning techniques, like >those used in the top commercial programs. For the moment, I compensate with >extensions. Maybe it is not possible to do both. Maybe it is the same thing, >from a certain point of view. > >But I have learned a few important things : > >1) You must never dismiss some thing that doesn't work now. Maybe in a year from >now, It will work. >2) You must never assume that something that works in someone else program wil >work in your program. >3) Like Christophe Theron rightly says, you must believe in statistics. Your >testing methodology must be extremely well thought out. >4) If you hear someone say "this algorithm sucks", or "it doesn't work", don't >forget to add "for me" to the sentence. You must try it for yourself. >5) Sometimes, you should completely leave the world of chess programming (even >for one or two weeks). Some ideas have a way of being found only when you don't >think about them ! Great post! I only wish the whole chess world could get its hands on copies of Chess Wizard.
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