Author: Georg v. Zimmermann
Date: 04:22:00 07/02/03
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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? IMHO Rainer Feldmann uses bad terminology. A fail high node is - at least by my definition - indeed a node where one subtree returns a value above beta, you therefor "fail high" and return (value or beta, depending on if you use fail soft). What he intends to say is probably : " a fail high REDUCTION node is a node 'v' with a search window of [alpha,beta] at which >a static evaluation function 'c' produces a cutoff. " The technic he describes sounds a lot more error prone than null move to me, at least in tactical situations. Georg
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