Author: Bas Hamstra
Date: 10:46:08 08/08/99
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On August 08, 1999 at 13:06:59, Robert Hyatt wrote: >On August 08, 1999 at 12:41:07, Bas Hamstra wrote: > >>Bob, >> >>I read that thread with interest. I am experimenting with the qsearch (and SEE) >>too. Currently I use only check evasions in the qsearch. I don't like it when >>the qsearch stumbles per accident on a mate and it doesn't see it's a mate. And >>it returning a bogus Eval because Eval was > Beta. With evasions only that won't >>happen. It doesn't cost an awful lot of nodes and it sees mates quicker. >> > >I did this sort of stuff in Cray Blitz, but I controlled the 'check evasion' >stuff... ie if the first q-search move was a check, then I would evade at >qsearch ply-2, and if the move at qsearch ply-3 was a check, I would evade at >ply-4, etc. IE so long as _every_ qsearch ply for one side was a check >evasion, I evaded at N+2. But the minute the side in question was not in >check, it could stand pat. And I would do no more evasions for that side below >this node since they would not lead to a forced mate (the side on move can >always stand pat and not play a capture if all captures lead to mate...) Interesting. But you did also checking moves in the qsearch that are not captures, which I don't. The reason why it doesn't cost a lot of nodes, I forgot to mention, is that when InCheck I try normal captures first. Just like normal. However if after *every* capture my king is still in check (so no captures were legal) *then* I do evasions. Note that I don't allow Eval>Beta cutoffs, when in Check. It helps me see WAC141. Regards, Bas Hamstra. >>And I can confirm that SEE ordering doesn't give a great reduction in treesize >>but throwing out losers is a win. However I did a MVV/LVA scheme while only >>throwing out "obvious" losers. That is, when A > D and after the capture A is >>hanging, throw it out. That's much faster than SEE. If I'm not mistaken it did >>not do much worse than SEE. > > >Note that I don't use SEE on _all_ q-search captures... There are plenty that >can be weeded out without calling SEE at all... IE I use a trick just like >yours to avoid calling Swap() in cases where the capture is obviously bad... > > > > >> >>(tried to reply to some posts yesterday, but couldn't post) >> >>Regards, >>Bas Hamstra.
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