Author: Robert Hyatt
Date: 13:16:14 06/23/00
Go up one level in this thread
On June 23, 2000 at 14:27:32, Andrew Dados wrote: >On June 23, 2000 at 02:06:27, Bruce Moreland wrote: > >>On June 22, 2000 at 17:38:37, Vincent Diepeveen wrote: >> >>>On June 22, 2000 at 08:29:03, Robert Hyatt wrote: >>> >>>>On June 22, 2000 at 07:55:53, Vincent Diepeveen wrote: >>>> >>>>>On June 21, 2000 at 11:12:23, Robert Hyatt wrote: >>>>> >>>>>>On June 21, 2000 at 11:03:42, David Rasmussen wrote: >>>>>> >>>>>>>I find that a lot of the games that my program loses, it loses because it >>>>>>>doesn't search checking moves in qsearch. >>>>>>>Anyway, how do people do that most effectively? I would like not to generate all >>>>>>>moves in the qsearch (just the captures), but then I will miss the noncapturing >>>>>>>checks. >>>>>> >>>>>> >>>>>>I did them in Cray Blitz, and in early versions of Crafty. But I haven't >>>>>>done checks in the q-search since just prior to the Jakarta WMCCC event. >>>>>> >>>>>>You can control them to an extent... ie when you get to the q-search, you >>>>>>can consider a check. But if you look at a capture at the first ply or 2, >>>>>>then there is little point in doing checks deeper in the q-search because the >>>>>>'stand pat' will allow you to avoid the checks totally, earlier in the >>>>>>tree. >>>>> >>>>>76% of all checks give a cutoff in DIEP in qsearch >>>>>on average a check improves score with 2.9 pawns >>>> >>>>That is fine. But if 76% of checks are giving cutoffs, you have a problem >>>>somewhere else, because _most_ cutoffs should be produced by captures, not by >>>>checks. >>> >>>That's pretty hard to measure in a realtime program and i disagree here. >>>If you're in check, then you don't need to evaluate and have limited choice, >>>so the number of nodes you cycles you waste when being in check is >>>quite limited. >>> >>>3 out of 4 checks giving a cutoff in a position which wasn't a cut node >>>without trying the check (otherwise beta pruning) is pretty good i think. >>> >>>I'm sure most don't get such a good cut rate. >> >>I don't see how this makes any sense. Why would a check give a cutoff unless >>it's a mate, a capture, or the subject of an eval function bonus? >> >>bruce > >[D]4k3/8/8/8/r7/8/6Q1/4K3 w - - > >We're in qsearch here. Qxc6+ Kxx QxR will give a cutoff, no? >-Andrew- So will an eval term that says KQ vs KR is an easy win if the queen isn't lost. But for every such tactic you find in the q-search, there are even more you miss by not considering anything but checks and captures. Why make the q-search _bigger_ if it is already horribly inaccurate?
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