Author: Bas Hamstra
Date: 16:09:06 11/09/03
Go up one level in this thread
On November 09, 2003 at 02:13:47, Christophe Theron wrote: >On November 09, 2003 at 00:36:30, Daniel Shawul wrote: > >> I am confused about futility pruning at frontier nodes(depth==1). >>well,the theory says if >> mat(node at depth==1) + mat(gain of move) + maximum positional score < alpha >> prune all non-checking moves.Ok! Well what I don't understand here is >>if we don't use the pruning technique here the stand pat cut off will do it >>at the quiescence node.So what we saved here is just making the move,right? >>E.Heinz says FP At frontier shrinks the tree by 60%.Please help me out here. >> >>regards >>Daniel > > > >You cannot stand pat here. You have not reached the QSearch yet. > >You are at one ply from the horizon (remaining_depth==1). You cannot just stand >pat. But if you see that the minimum score (alpha) that you have to reach to >make this branch relevant is well above what you can expect from a particular >move, just don't even try this move (unless it's a check) because it is clearly >futile to try it. > > > > Christophe What he means if if you do not futility prune, you make the move and then goto qsearch. Where you quickly find out Score >= Beta so FP saves only that move (in an inaccurate way). Bas.
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