Author: Robert Hyatt
Date: 19:24:58 02/27/06
Go up one level in this thread
On February 27, 2006 at 19:48:49, Tom Likens wrote: >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 actually I believe you are right. I think I actually noticed this in testing but had forgotten. And one _could_ force this to happen. I stuff the PV into the hash table at the end of each iteration, just in case some of the entries got overwritten. I could stuff a significant value (say 2* history threashold) into the corresponding history values just as easily...
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