Author: Sune Fischer
Date: 04:35:12 08/24/03
Go up one level in this thread
On August 24, 2003 at 06:35:45, Omid David Tabibi wrote: >>Like Uri suggested you can first check if the square of the attacker is attacked >>by a sliding piece, if not no need to look behind it as it can't expose >>anything. > >Sure, but what do you do if you find that an attacker is attacked by a sliding >piece? How do you incorporate that attacker with the lookup table's result? > >For example, there are a number of attackers who attack a square, and a number >of defenders; the lookup gives the value -3, i.e., a losing capture. Also assume >that there is an x-ray queen behind one of your attacking pieces. How do you >incorporate that queen into that -3 value? > Hmm you have not understood completely how the table works I think. As Uri also did point out, a table lookup for SEE doesn't work with this ploy. I'm not sure such a table can even be constructed, one could compute the number of bits theoreticly required by a crafty type SEE. I suspect such a table would be huge. >>I also don't fully agree that qsearch is all about inaccuracies, think about it, >>all branches terminate in a qsearch, so everything sent down the tree must be >>garbage....? > >Until a while ago at least, Junior did not have any quiescence search at all... I think quiescence is too broad a term to say it didn't, every program faces a quiescence problem at the leaves, so it must have done something. >Besides, even an "accurate" SEE isn't accurate at all: I would describle SEE as being accurate, possibly overkill if anything. However in my book "accurate" does not mean flawless or perfect, it means "pretty darn good". "pretty accurate" might be more precise :) >3r2k1/pp1n1ppp/2p2q2/8/2PR4/2B5/PPQ2PPP/6K1 w - - 0 1 > >SEE will deem Rxd7 a losing capture, while it's actually a winning one. If you >want a more accurate quiescence, use MVV/LVA. No perfect scheme exists, chess is too complex for that (that is why we do the search in the first place:). It's just a matter of optimizing the speed vs. accuracy design. -S.
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