Author: Michael Neish
Date: 06:14:03 01/07/06
I hope this doesn't come across as too much of a beginner's question. Is it beyond question that null move improves search? The reason I ask is that I recently dusted off my old program, and ran a few tests on it, and was dismayed to discover that I seem to be getting very little benefit from using it. This is trying out different parameters (R-2, R-3, at depth >2, >3, etc.). I thought the whole idea of using null was that you could get a swifter cut-off and hence reduce the number of nodes searched to reach a given depth, but I'm getting little or no reduction at all, and in some cases even an increase. Depending on the position, and the parameters used, about 40-60% of null moves performed fail high and return immediately. The remainder move on to a normal search. So I thought that, in my program's case, perhaps the nodes wasted on null move searches that don't fail high is almost the same as those saved by null move searches that do fail high. Does this make sense? Is a cut-off rate of about 40-60% to be expected, or should it be higher? For what it's worth, around 80% of nodes in the tree are in Quiesce(). Could this have something to do with it? So barring an error in my implementation, can anyone comment on why null move is giving me virtually null benefit? Thanks in advance to anyone who takes the time to reply. Regards, Mike.
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