Author: Ralph Stoesser
Date: 16:34:28 07/01/03
Go up one level in this thread
On July 01, 2003 at 18:24:43, Omid David Tabibi wrote: >On July 01, 2003 at 18:19:44, Ralph Stoesser wrote: > >>On July 01, 2003 at 18:10:04, Uri Blass wrote: >> >>>On July 01, 2003 at 17:34:47, Russell Reagan wrote: >>> >>>>From "Fail High Reductions by Rainer Feldmann" >>>> >>>>"...a fail high node is a node 'v' with a search window of [alpha,beta] at which >>>>a static evaluation function 'c' produces a cutoff. The FHR-algorithm reduces >>>>the search depths at these fail high nodes thus searching their subtrees with >>>>less effort." >>>> >>>>Their subtrees? I thought fail high nodes didn't have subtrees, and that you >>>>return beta at a fail high node. I must be misunderstanding something. Could >>>>someone give a simple explaination of how fail high reductions work? >>> >>>If I understand correctly the idea is that you evaluate a position that is not a >>>leaf and the static evaluation is not in the window of [alpha,beta] so you >>>reduce the depth. >>> >>>Example:when you analyze e4 Nf6 Qh5 Nxh5 your evaluation is a queen advantage >>>for black and you can be almost sure of fail high so instead of searching to >>>remaining depth of 7 you may decide to search to a smaller depth. >>> >>>Uri >> >>I think that's right. This is similar to the Nullmove technique, but not that >>radical, because you only reduce the search depth instead of cutoff the whole >>subtree. > >... which is called verified null-mvoe pruning :) > >> >>Ralph Now, after I have read your interesting article about it, I would tend to agree :)
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