Author: Robert Hyatt
Date: 16:41:13 09/28/04
Go up one level in this thread
On September 28, 2004 at 05:03:30, Peter Fendrich wrote: >On September 27, 2004 at 17:00:28, Robert Hyatt wrote: > >>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... > >Both alpha-w and beta-w. Wouldn't that make the hash table even more unstable >than it is already? I mean "put entry" with one window in the first search and >"get entry" with another window in the next re-search? >/Peter That's just "part of the game" yes...
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