Author: Tom Likens
Date: 16:48:49 02/27/06
Go up one level in this thread
On February 27, 2006 at 19:36:10, Tom Likens wrote: >On February 27, 2006 at 13:41:57, Robert Hyatt wrote: > >>On February 27, 2006 at 12:46:40, Frank Phillips wrote: >> >>>So you do this at only (expected) cut nodes? >>>Tord seems to imply at anything other than pvNodes. >>> >>>Frank >> >> >>I do it at _all_ nodes. I think Tord does as well. The problem is it is >>impossible to predict with high accuracy whether a node is CUT or ALL (btw, this >>is only useful at ALL nodes, since we have to search all moves and reducing the >>depth reduces the effort required to accomplish that). > >Bob/Tord, > >I just got to my hotel (I'm on a business trip for the next few days) and I >see CCT8 has sparked a number of interesting threads. Reductions are >especially fertile ground. > >I'd be careful reducing at PV nodes. I saw a significant drop in djinn's >positional strength when I applied this at PV nodes. At the very least >you might want to skip it at nodes where alpha/beta == RootAlpha/RootBeta. >Ideally, as you mentioned you only want to apply this at ALL nodes. Actually, thinking a bit more about this--makes me wonder why the history table didn't prevent these nodes from being reduced anyway. It may be time for an experiment to determine how often a "PV" node doesn't have any history table information. I would think intuitively this should not happen very often. >I've also experimented with "flipping" CUT nodes to ALL nodes if we search >more than 'x' moves at a CUT node without a fail-high or an improvement >in the score. Once the flip occurs all the nodes below are toggled in the >normal CUT -> ALL -> CUT etc., and these nodes become eligible for reduction. > >Also do you allow multiple recursive reductions or do you limit them? I've >applied the adaptive reduction idea a while back, with mixed results. It's >likely I didn't test this enough because I was in the middle of a major >project at work and could only give it a small percentage of my attention :-( > >regards, >--tom
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