Author: Robert Hyatt
Date: 07:40:49 10/05/99
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On October 05, 1999 at 05:25:21, Bas Hamstra wrote: >What are good ways to cut down the number of evals? I saw Bob Hyatt post that he >could easily double NPS when using "Lazy Eval". > >What is a correct way to do that? Is there more to it than the qsearch "delta" >type of pruning? > > >Regards, >Bas Hamstra. The idea is that in general, your eval _must_ return scores > alpha and < beta, or they are not useful, correct? (please ignore this if you use mtd(f) of course, as it is more complicated then). Suppose alpha=-.30 and beta=+.30. When you get into your eval, if you can figure out that you can't possible bring the score within that window, you can return the appropriate bound quickly. IE if you come in and material is at -9.00 (You have lost a queen somewhere in this path) then do you have an eval term that can add +9.00 to the score to bring it inside the window? If not, you can either return -9.00, or the more safe -.30, since the score is at least that bad. You can use this at several points to bail out after you are sure you can't get "in the box" with the score...
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