Author: Dan Honeycutt
Date: 10:47:41 08/07/04
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On August 07, 2004 at 13:40:16, Dan Honeycutt wrote: >On August 07, 2004 at 13:00:31, Stuart Cracraft wrote: > >>So I heard a lot about SEE from a lot of people >>and was fortunate enough to receive some good code >>from Alessandro. I implemented and tested it with >>many test cases and in all cases it gave the >>expected return from the exchange ok. >> >>Then with some other help I implemented this in >>the capture search. >> >>This program has some things that make SEE() not >>give a good result, in fact slightly worse (fewer >>nodes in same time) -- no speedup. >> >>1) evaluator is material and pc/sq lookup only >>2) routine to find attackers/defenders (to give to see) >> is not much faster or slower than makemv() >>3) I order all moves partly with MVV/LVA but do not >> discard directly on that unless the alpha/beta/pvs >> says to disard/cutoff. >> >>With these, the program did not speedup with SEE >>and slowed down. The program is PVS with null move. >> >>So that is the story -- I will leave the code in >>for a future day and future need. >> >>If someone with #1 and #2 got a good speedup from SEE, >>let me know. I am doing something wrong in that case. >>Or if you think there is some other way SEE can be used >>advantageously, let me know. Currently I only have it >>in the capture search since that's where I heard it had >>the most effect. >> >>Stuart > > >Stuart: >What captures are you discarding in qsearch? ie > >if (see < 0) discard_capture; >if (see + standpat < alpha) discard_capture; >if (see + standpat + margin < alpha) discard_capture; > >You may want to tinker with this some. For me the third one with a margin of a >pawn or 2 works best. > >Dan H. I should add I also do: if (mvv_lva + standpat + margin >= alpha) keep_capture_and_skip_see; mvv_lva is victim value - attackor value. Dan H.
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