Author: Robert Hyatt
Date: 19:54:33 08/26/04
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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 can immagine that when one gets a cutoff, the rest of the moves don't have to >>be generated (captures vs non-captures). However, in leaf nodes, one is very >>likely to generated all the moves anyway. >> >>Has anyone compared these?
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