Author: Vincent Diepeveen
Date: 11:07:37 01/01/02
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On January 01, 2002 at 13:53:37, J. Wesley Cleveland wrote: >On January 01, 2002 at 13:10:33, Vincent Diepeveen wrote: > >>On December 31, 2001 at 21:32:24, J. Wesley Cleveland wrote: >> >>>On December 31, 2001 at 05:28:54, Dann Corbit wrote: >>> >>>>On December 31, 2001 at 05:26:11, Michel Langeveld wrote: >>>>>I want to check how efficient Nullmover is. >>>> >>>>By how often you fail high on your first choice. >>> >>>Note that this is somewhat deceptive, e.g. crafty gets about 90% failhighs >>>first, but often visits twice as many nodes as the minimum. A more accurate way >>>is to compare the total number of nodes visited to the minimun. The recursive >>>algorithm to count this is relatively straightforward: >>> >>>if (failhigh node) >>> minimum_nodes = minimum_nodes(fail_high move) + 1 >>>else >>> minimum nodes = sum for all legal moves(1 + minimum_nodes(move)) >> >>Problem to determine minimum is nullmove reduction factor. >>It completely depends upon how you extend crazy tactical moves because >>after tactical move your nullmove will nearly always fail. > >If a nullmove causes a cutoff, the nodes visited are part of the minimum. >Hashing causes much larger problems, as a move which appears to be unnecessary >could add hash table entries that cause cutoffs later. I think of this as a >rough estimate more than an exact figure, but believe it is much more accurate >than fail high first percentage. You can never proof a minimum search tree for iteration n where n is big with nullmove and hashtables. That's impossible, it's even evaluation dependant. theoretic minimum for 10 ply search with always evaluation = 0 and using nullmove R=3 is pretty little. like 2000 nodes or so ?
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