Author: Bo Persson
Date: 13:22:49 12/07/00
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On December 07, 2000 at 05:34:08, Leen Ammeraal wrote: >On December 07, 2000 at 04:23:48, Andrew Williams wrote: > [...} >> >>My program uses MTD(f). It stores an upper bound and a lower bound >>for each position in the table (these are set to +HUGE and -HUGE in >>empty entries). It also stores a draft for each bound in the same >>hash entry (these are both set to -100 or something in an empty record). >> >>Cheers >> >>Andrew > > >Andrew, thanks. >I had just come to the same conclusion: storing >two bounds requires storing a depth (or draft) for >each, and I have already been implementing this >and am now testing it. >I still fail to see why this should only be useful >for MTD(f), not for alpha/beta or negascout. > >Leen Yes, I have been doing like this since I started trying out MTD(f), about a year ago. Having both bounds is useful for negascout as well (accidentally tried that in an intermediate program version...), but absolutely *essential* to get any performance from MTD(f) re-searches, as it might swing back and forth at the end of the search (closing in on the final score with a slight overshoot in each direction). Contrary to what Bob says in another part of the thread, I think that storing both bounds in the same entry actually *saves* space, as you otherwise would have empty best moves in the upperbound nodes. Bo Persson bop@malmo.mail.telia.com
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