Author: Robert Hyatt
Date: 16:46:39 09/15/04
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On September 15, 2004 at 18:15:33, Gerd Isenberg wrote: ><snip> >>>>Hsu's paper defined singular extensiosn for PV nodes and CUT nodes. His paper >>>>said "we have found no useful definition for a singular move at an ALL node >>>>however.." >>> >>>Hmm isn't the definition simply that there is one move which is by a certain >>>amount better than all others, independent on pv-, cut- and all-node? >> >>No. There is a precise definition of a singular move, but the test is only >>defined for PV and CUT nodes. At an ALL node there is absolutely no way to >>determine if one move is better than all others. > >Maybe with fail soft and altered zero window bounds to check for one > score > alpha - SMALL_MARGIN >while all others are far below > score <= alpha - BIG_MARGIN > Won't work. At fail-high nodes (the next one down in the tree) we don't look for the _best_ move so that you get good scores backed up for each refutation at the previous ply, we just find a "good move". Trying to pick out the best move at an "ALL" node is impossible for that reason, unless you do a true minmax search rather than alpha/beta > >> >> >> >>> >>>Probably the forced situation, that there is only _one_ move (e.g. becomes >>>alpha while all others are less alpha-margin), makes it worth to look deeper to >>>look whether the all-node becomes a singular cut node or improves alpha, with >>>possible influence at the root. >> >>That test won't work. Tests where the value is <= alpha or <= alpha-margin are >>really meaningless in the context of alpha/beta/minmax search. That is why they >>could not define a workable test for singularity at ALL nodes. > >I see. > ><snip>
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