Author: Stuart Cracraft
Date: 10:50:46 08/07/04
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On August 07, 2004 at 13:47:41, Dan Honeycutt wrote: >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. Dan - thanks for the input. What value of standpat do you use? (Assume the see() routine does all its internal standpat in its minimax.) Stuart
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