Author: Robert Hyatt
Date: 10:10:33 03/16/04
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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??? 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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