Author: Omid David Tabibi
Date: 15:24:43 07/01/03
Go up one level in this thread
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
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