Author: David Rasmussen
Date: 00:20:26 01/12/01
My program Chezzz, and most of the programs I've been learning from and looking at, has only little or moderate selectivity. Maybe I will keep it that way in Chezzz, but what are the possibilities? As far as I know, there are two general kinds of selectivity as currently used in "normal" alpha-beta based chess programs. 1. Extensions 2. Forward pruning I would like to know what hints and tricks you guys have about extensions, unusual extensions, how to limit extensions, when not to extend etc. But most of all, I would like to know about successful (I know this is somewhat subjective) forward pruning techniques, that are actually used in programs. I compared my programs performance on the position below, with what Christophe Theron posted from GT. At depth 10 the nodes searched by each programs are appx. GT : 1.290.000 Crafty : 13.500.000 Chezzz : 12.500.000 So Crafty and Chezzz is the same, and they are both very conservative in regard to selectivity IMO. I know that this is a choice and that one way is not better than the other, but I would still like to know how programs such as GT can get such a low node count. Now I know that GT is highly optimized, and that it has probably taken a long time get as "efficent" as GT. But I would still like to know as much as possible or at least the basics about how to forward prune succesfully like this. [D]2r1k2r/5pp1/4p3/ppqpP3/4bQPP/1B6/PPP2R1R/2K5 b k - 0 1
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