Author: Gerd Isenberg
Date: 07:49:41 07/02/03
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On July 02, 2003 at 07:22:00, Georg v. Zimmermann 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? > >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 Hi George, If i remember well, Rainer Feldmann's FHR is based on the NullMove observation. Instead of foreward pruning, FHR reduce depth if a NullMove fail high occurs. Regards, Gerd
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