Author: Robert Hyatt
Date: 14:00:28 09/27/04
Go up one level in this thread
On September 27, 2004 at 14:21:51, Stuart Cracraft wrote: >So when in PVS I've searched my first move, and it is a PV >move as well, with search returning value then I do a depth-2 >search on all other moves and if none -search(depth-2,-beta-MARGIN,- >alpha-MARGIN) <= -beta-MARGIN, where MARGIN is set to 3/4 of a pawn, >then the PV move is singular and I re-search it with depth instead of depth-1 >and use the returned value as my score against which to >measure all other non-PV moves against in the normal part >of the search, searching them to depth-1. > >Is the above wrong? > >Stuart It is wrong. Search the first move with the normal window. Search the _remaining_ moves with an offset window alpha-w, beta-w. If all still fail low (which they should do if the first move is best) then the first move is singular. re-search it again with a deeper search. If one of the remaining moves fails high on the offset window search, now you have a problem. Is this move better than the best move? If not the best move is not singular. But, this move could itself be singular so you have to test that hypothesis by re-searching the first move with a window lowered by the usual offset from the score returned by the second move that failed high. Repeat until sick or finished. You are describing what is done for determining singularity at fail-high nodes where only one move is normally searched before returning, but you do the "cheaper" searches to try to prove singilarity anyway and extend even a fail-high move one ply...
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