Author: Robert Hyatt
Date: 16:06:03 08/18/00
Go up one level in this thread
On August 18, 2000 at 14:48:43, Dave Gomboc wrote: >On August 18, 2000 at 13:53:16, J. Wesley Cleveland wrote: > >>On August 18, 2000 at 09:23:38, Robert Hyatt wrote: >> >>>On August 17, 2000 at 18:05:41, Gian-Carlo Pascutto wrote: >>> >>>>On August 17, 2000 at 14:43:08, J. Wesley Cleveland wrote: >>>> >>>>>When you have a fail-low in a deep search where the value drops significantly, >>>>>finding an alternate move can take a very long time. This is largely because >the >>>>>values in the hash table are largely useless, so in effect we are researching >>>>>the entire tree. It seems to me one should use iterative deepening, and start >>>>>from ply 1 again. >>>> >>>>This technique has been described by Schaeffer a long time ago... >>>> >>>>(Obvious question: Why is nearly no-one doing it?) >>>> >>>>-- >>>>GCP >>> >>> >>>I'm not sure what you mean by described a long time ago. But there is a big >>>problem. If you start over at 1 ply, you don't get the fail low score. You >>>find (again) the _wrong_ move, until you get deep enough. When there is a big >>>score swing between two iterations, you take your lumps. There is no way to >>>cheat alpha/beta there. >> >>You should get the fail low score, since it is in the hash table. They should >>stay there as they are analyzed to a greater depth than you are likely to get >>to. > >Yes, the technique relies upon the information from the deeper searches being >present and used to perform cutoffs at shallower searches. > >Dave Doesn't this sound _gross_ time-wise? You find another move that doesn't fail low, until the last iteration when the truth is found. If you repeat this a few times, it seems worse than just searching for a new best move???
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