Author: Robert Hyatt
Date: 20:52:19 09/01/01
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On September 01, 2001 at 10:57:12, Steve Maughan wrote: >Vincent, > >>You are entirely right Ed, i have singular extensions inside diep now >>and play with them turned on tournaments now. first tournament i played >>with them turned on was back in 1994 the dutch open championship, >>but my implementation sucked bigtime there. Then in paderborn 2001 i >>used a better implementation with big reduction factor (R=3) and >>also in combination with other extensions. > >How do you implement SE? Or how did the DB/DT team do it? Are there any online >papers? I've heard that SE must be dynamic so how does one detect if a move is >singular? Are you doing some reduced depth search (R=3) prior to the proper >search? What bounds? > >Thanks, > >Steve Maughan The "complete" way to do it is as follows: 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 moves fail 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. On a fail-high move, you have to search the remainder of the moves, rather than just stopping the search. Again using an offset window, but with a shallower depth than normal. If the fail-high move proves to be singular, or the best PV move proves to be singular, it is re-searched to 1 ply deeper. It is complex and it takes some search overhead. There is another way that is cheaper but significantly less accurate...
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