Author: Dieter Buerssner
Date: 03:44:45 06/19/05
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On June 18, 2005 at 15:27:32, Vasik Rajlich wrote: Thanks for elaborating - I agree with everything. >>Lazy eval can be made "soft", futility pruning, too. >> > >As far as I can tell, a lazy eval will always cost you some softness. Of course. (Isn't "soft" really anti intuitive - I am no native English speaker, but I'd imagine the bound gets softer, not harder ...) >Regarding futility pruning in q-search, how will you return a good fail-soft >value here: This is not really futility pruning specific, I think >[D] r1bqk1nr/pppp1ppp/8/2b1p3/3nP3/2NP1N2/PPP1BPPP/R2QK2R w KQkq - 6 1 > >White is down a piece and needs to get to +0.50 (that's our window, let's say). >We'd like q-search to return a fail-soft of -3.00. But: white tries 1. Nxd4, and >black fails high by standing pat. How do you avoid returning a fail soft of 0.00 >or so? Exactly. Basic qsearch without any tricks will do this by allowing a standpat score. Perhaps the most important reason, we typically get back fail soft scores of alpha for all moves at the root besides the PV. Regards, Dieter
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