Author: Will Singleton
Date: 15:59:52 03/09/99
Go up one level in this thread
On March 09, 1999 at 16:34:09, Dan Homan wrote: >On March 09, 1999 at 16:26:39, Bruce Moreland wrote: > >> >>On March 09, 1999 at 16:17:24, Dan Homan wrote: >> >>>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 >> >>I ran with a +- 32767 window for months and didn't notice. >> >>bruce > >I was thinking some more about this and the only place I can see a major >improvement from using a window is on positions where you will >fail high and change the move you will play... With the window, >you can decide to play this move before you know how much better >it is, sometimes it takes quite a while (x2 the time) to resolve >the higher score... > - Dan I agree with that, but if you don't allow your time to expire until resolving a move (when time is available), then it shouldn't be an issue. Will
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