Author: Robert Hyatt
Date: 06:48:48 09/02/01
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On September 02, 2001 at 04:10:02, Steve Maughan wrote: >Bob, > >Thanks for the reply! > >>On a PV move, you search the first move and get the score. You search the >>remainder of the moves with the window alpha-N, beta-N, where N is somewhere >>around 1/2 a pawn or whatever singular margin you want to use. If all the >>movesfail low, then you know the first move is at least 1/2 pawn better than >>all the rest, which means it is singular. Of course, if one of the other (not >>the first move) fails high, you have some work to do to determine if it is >>singularly better than all the rest, including the first one. > >Hmmm, that seems like quite a bit of overhead. If move ordering is good, this is very small. If move ordering is not so good, this can be very bad, of course. > >>It is complex and it takes some search overhead. There is another way that is >>cheaper but significantly less accurate... > >Now you're got me thinking - what's the cheaper way? Any hints? Do a shallow search up front, to see if the shallow search reveals that one move is better than the rest by some significant margin. Then do your normal search, but extend that one "singular" move when you get to it. You have to search all moves to some reduced depth to make this affordable, which is not quite the same as DB's implementation or result. > >Thanks anyway, > >Steve
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