Author: Jeremiah Penery
Date: 21:09:49 11/20/02
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On November 20, 2002 at 22:05:29, Robert Hyatt wrote: >On November 20, 2002 at 16:55:41, Gian-Carlo Pascutto wrote: > >>Nullmove in Deep Sjeng uses an algorithm of my own, but I can >>switch it back to other systems easily. I did so for running >>a few tests. >> >>I made a version which uses Heinz Adaptive Nullmove Pruning >>and a version which uses your verification nullmove. > >This would seem to be a bit harder than at first glance. They say that >if the normal null-move search fails high, then do a D-1 regular search >to verify that, but while in that verification search, no further >verification searches are done, meaning that the normal null-move search >fail-high is treated just like we do it today.. > >I'm going to experiment with this myself, just for fun, but it seems that you >need to pass some sort of flag down thru the search calls indicating that >you are either below a verification-search node or not so that recursive >verification searches are not done... I tried implementing it in Crafty, as it is done in the pseudo-code in the paper. I wasn't sure exactly where to place the block with the goto, and since Crafty has no 'best' variable in search, I wasn't sure what to put there either. However, the algorithm did seem to work ok, though it didn't result in a smaller tree that I could tell. I didn't get a chance to compare it to the normal Crafty in many positions, or for a very long time, however.
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