Author: Stuart Cracraft
Date: 13:44:51 08/07/04
Go up one level in this thread
On August 07, 2004 at 15:28:07, Michael Henderson wrote: >On August 07, 2004 at 13:50:46, Stuart Cracraft wrote: > >>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 > >Are you using SEE to order captures in the non-qsearch? I tried these (both worse than no SEE for me) SEE to order captures in qsearch and non-q search SEE to avoid searching losing captures altogether in qsearch Stuart
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