Author: Andrew Williams
Date: 16:27:32 06/25/04
Go up one level in this thread
On June 25, 2004 at 16:15:44, Stuart Cracraft wrote: >So, normally in the literature I've read >(and code I've implemented, it's been to >do a null move search with R set to 2, >so search(...depth-1-R). > >But in large searches of 8, 9, 10, 11 and >beyond in full width searches, the reduction >of 2 does not seem to help as much as >larger reductions due to the much smaller >subtrees that the null move searches has >to search with an R of 2. > >My question is: what have people done >to experiment with larger figures of R and >verify the return value is effective >and horrid moves aren't produced? > >I've used R set to ply/2 and ply-2 >where ply is the original target depth >of the overall iteration. The savings >in time is substantial and the moves >look the same or as good, the tree searched is >drastically smaller of course, but >I am worried about quality. > >Is R of 2 or 3 a holdover from the slow >computing days in the literature and nowadays >you are using higher settings? > >Assume everything else about the null move >search is held the same (not done in endgames, >not done in the original position, no more >than 1 null move in a row during the search >without an intervening normal move, etc.) > >Thanks ahead, > >Stuart Ernst Heinz has published interesting papers on adaptive null move pruning (varying R with remaining depth and remaining material). I would guess that this is pretty standard now, at least among amateurs. Omid David Tabibi has published recently on verified null move pruning. Cheers Andrew
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