Author: Robert Hyatt
Date: 13:21:23 03/16/04
Go up one level in this thread
On March 16, 2004 at 15:31:45, Sune Fischer wrote: >On March 16, 2004 at 13:10:33, Robert Hyatt wrote: > >>On March 16, 2004 at 12:56:29, Sune Fischer wrote: >> >>>On March 16, 2004 at 12:33:30, Robert Hyatt wrote: >>> >>>>> 1> apply HH to the subtrees with that shallow (5-7 ply) remaining depth, and >>>>> reset them for every other subtree, ofcourse >>>>> 2> apply HH to the top (5-7 ply) only >>>>> >>>>>It did not have the effect I thought it would have... >>>>> >>>>>Any ideas on the topic? Which should be doing better anyway? Or apply them both! >>>>> >>>>>Renze >>>> >>>>Neither. At the root, before starting a brand new search (not a new iteration) >>>>age the counters... IE in Crafty, in "main()" I shift the counters right 8 bits >>>>(divide them by 256). This ages old history counters away over a few moves, >>>>without losing important values instantly... >>> >>>I think it is better to rescale it once and a while if you analyze for a long >>>time on each move. >>> >>>What happens is that the table will get filled with search information and as >>>the search moves into a new branch (a branch which is largely uncorrelated with >>>previous ones) the new search information will have to compete with the old one >>>and that can/will result in decreased efficiency. >>> >>>If you rescale it every x nodes or so, the information keeps being fresh. >>> >>>Anyway, this is what seems to produce the lowest nodes to solution numbers in my >>>tests. >>>Every man is his own best tester :) >>> >>>-S. >> >> >>I think we are different because I use _both_ approaches... killers and history >>moves. Killers are definitely local. History is a "global killer". Perhaps if >>you don't do both, your results could be different from mine??? > >I use killers also, but I don't consider HH to be "global" as such. >I consider HH to be valid in the neighborhood of where it is constructed, >globally I see no reason why it should work well. > >I think if it did work well globally there would be no need to build it >on-the-fly, one could just seed the table before the search with precalculated >data. > >My view is that the history tables provides a form of probability matrix. >It tells us which type of move has the best probability of producing a cutoff. >The the more local the matrix is, the more accurate does it describe the >probabilities for the current position. > >As a global table I believe it will become quite smeared and lose some of its >sting. > >Anyway it should be a quick test to see which (for Crafty) produces the smallest >tree :) > The idea is that a move that is good at ply 15 might also be good at ply 3... And vice-versa... >-S. >>But in any case, I depend on killers for local cutoff moves, and I use history >>when all else has failed...
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