Author: Stuart Cracraft
Date: 20:08:52 08/26/04
Go up one level in this thread
On August 26, 2004 at 22:54:33, Robert Hyatt wrote: >On August 26, 2004 at 22:48:52, Pham Hong Nguyen wrote: > >>On August 26, 2004 at 16:25:07, Lance Perkins wrote: >> >>>After seeing the posted NextMove code, I wonder how much better this is than >>>simply generating all the moves and then sorting them in one go. >>> >>>This code is a little to complex and tool long for my liking, but if it offers a >>>very significant gain, maybe I should give it a second look. >> >> >>If you try it, you may change your mind. For chess, imagination may be quite >>different from practice :) >> >>The gain depends much on your board representation. You may notice that the >>bitboard could generate the capture moves faster than the non-capture ones. That >>is why Crafty generates moves in phases in hope to avoid genarating non-capture >>moves. But if your board is an array style (like mine), where both capture and >>non-capture moves could be generated by the same speed and the combination of >>them can save time in many cases, phase generation gains almost nothing (or >>negative thing). >> >>BTW, you are talking about a gain of 0-3% (for any kinds of board >>representations), it is not very significant gain as you wish. >> >>Pham > >The only reason I do it as I do is it is easy to generate captures by >themselves, and that has two advantages. > >(1) in the q-search I don't waste time generating non-captures. > >(2) in the capture part of the regular search I avoid the generation cost for >non captures, plus I don't have to skip over non-captures when sorting the >captures. It is a win. Not huge, not insignificant either... > I do #1. I don't do #2 but could. Another on that huge stack of things to implement, some day.
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