Author: Uri Blass
Date: 15:10:04 07/01/03
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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
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