Author: Don Dailey
Date: 18:10:04 01/28/98
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Hi Bruce, My own testing on earlier chess programs indicated a small but definite improvement by weighting moves near the root. I used depth from leaf nodes and use d * 2^n. I didn't do it for Bob's reason though. I felt that even if you felt the moves should be equally weighted, they were not since on the 2nd ply you have very little representation. And yet these are just the moves you would like to get ordered right. But your point is well taken, it's a rough idea and there may very well be better algorithms. Bob mentions that he gets little from killers. I'm sure this is because he already has the history heuristic. If I implement history heuristic first, I might think killer help very little, and visa versa. I remember reading an article years ago trying to show how each additional piece of knowledge helped the program, but the order the heuristics were presented significantly change the outcome. It turns out the first thing you put in the chess program seems like the one that helps the most. i.e. centralization may not seem important if you already have mobility, but if you do not, centralization is a HUGE improvement. The human mind is the same way. Studies show that we are influenced strongly by the order information is presented to us. We tend to use the first piece of information as a standard to judge the next by. - Don On January 28, 1998 at 18:02:40, Bruce Moreland wrote: > >On January 28, 1998 at 17:05:23, Robert Hyatt wrote: > >>from my early testing, you have to weight based on distance from the >>root... because I trust a move backed up as best near the root rather >>than one backed up as best near the tips. > >Possible topics: > >1) Whether or not it really matters how far the move is from the root, >since this is just being used to get a rough idea of what moves tend to >be good. I'm not sure it's intuitive that closer to the root is better, >since most applications of this heuristic will occur further from the >root, why not weight moves that tend to cause cutoffs way out there as >higher? > >2) Whether the moves that tend to have high history values in one >position also tend to have them in other positions, and if so, perhaps >some sort of static weighting system might be more efficient. > >bruce
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