Author: Dieter Buerssner
Date: 16:19:27 10/13/03
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On October 13, 2003 at 17:09:00, Omid David Tabibi wrote: >Actually I have found checks in the first ply of quiescence to be quite helpful >when used with null-move pruning. You mean helpful in test positions? >Assume that you are at depth = 3 and use R = >2, the null-move search will be conducted by depth 0, i.e., direct call to >quiescence. Also assume that no matter what you do, you are mate in 1. If you >have checks in quiescence the opponent will checkmate you immediately, returning >a mate score which in turn will trigger a mate trheat extension in the main >search. But if you don't do checks in quiescence you will miss the checkmate and >have a good chance of failing high on the null-move search resulting in a >cutoff. I.e., you think that the position is good enough to justify a cutoff >when in fact you are mate in 1! I totally agree with your analysis. >I think mainly for this reason adding checks in the first ply of quiescence >results in such an improved performance in solving test suites. But it doesn't >seem to be as helpful in actual games. And I made the same experience ... in reality it does not seem to help. I also tested to only call a qsearch with checks (that are not captures, the capturing checks I can handle in normal qsearch at first ply) after a null move. It was great in some test positions, but not in games. Perhaps my tests were not conducted well enough (too few games, too little tuning, whatever). It seems too logical, to at least try a qsearch with checks after a null move. I may try harder, soon. Regards, Dieter
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