Author: Dan Homan
Date: 13:17:24 03/09/99
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On March 09, 1999 at 14:34:49, Will Singleton wrote: > >Using PVS, I can't seem to demonstrate a clear benefit to using a small window >around the root score, as opposed to +-mate. > >Using a window of, for example, one-third pawn, if a move fails-high or low, it >takes fewer nodes to ascertain the move that caused the change, because you >don't have to find the real score right away. But then you've got to resolve >the new score, and that will take more nodes since you've got to re-search with >the relaxed window. > >And if, after a fail-high or low, you attempt to delay score resolution until >the next ply (to avoid the re-search at the same ply), it seems you might have >the problem of finding a worse move after the fail at the same ply, since you >don't know the real score yet. This would result in even more nodes being used. > >So I don't see much benefit, unless I'm doing something wrong (likely). On a >normal search, without any fails, I see either more or less nodes (between >windowing and +-mate), depending on the position. But not really much change. > >Any comment would be apppreciated. > >Will I've gone back and forth on this issue myself. My testing seems to show that a small window (+,- 1/4 pawn) is slightly (a couple of percent) faster when measured over a large number of problems than (+,- mate), but the coding is a bit more complicated. I think I'll test this again.... - Dan
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