Author: Ernst A. Heinz
Date: 09:26:11 04/07/00
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>> 3) does "razoring" mean pruning in general (or even alfa-beta method)? > >No, razoring is when you do futility pruning at the last ply of your full-width >search. No, Tom -- what you describe is not razoring but standard futility pruning at frontier nodes with a remaining search depth of 1 ply. > I think most people don't like it. Wrong again. Most people do not like razoring. Futility pruning at frontier nodes, however, is _theoretically sound_ for searchers with a capture-only quiescence and a futility margin that is at least as large as the maximal positional score produced by the static evaluation function. Standard futility pruning simply "lifts" stand-pat cutoffs from horizon nodes to frontier nodes. For more details, please see my article about "Extended Futility Pruning" in the ICCA Journal 21(2) and my book on "Scalable Search in Computer Chess" (http://supertech.lcs.mit.edu/~heinz/node1.html) for more details. >I tried it and all my test suite >scores went way down, even when the futility threshold was pretty conservative. >It just causes to the search to miss too much... According to my own experience and that of numerous others, this seems very strange. Maybe, you did not implement futility pruning but real razoring at frontier nodes. Your above quoted results sound like you did so. =Ernst=
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