Author: José Carlos
Date: 07:31:20 07/25/03
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On July 25, 2003 at 08:10:47, Uri Blass wrote: >On July 25, 2003 at 04:34:35, Amir Ban wrote: > >>On July 25, 2003 at 02:41:22, Dann Corbit wrote: >> >>>Now, a qsearch ending in checkmate may or may not really be a checkmate. After >>>all, we only tried certain moves and it could very well be that the checkmate >>>could be avoided. >>> >>>So, the burning question is... >>>What should we do when the qsearch ends in a mate? >>>There are lots of alternatives, from the primitive "return a mate" to "send a >>>danger signal up the tree and let the regular search deal with it" to >>>"extending" to... >>> >>>What is your favorite choice and why? >> >>I don't see where opinion comes in. In a node where all legal moves are not >>considered static eval is the minimum. >> >>Amir > >I think that it is not so simple. > >Suppose you find in the qsearch that all captures are losing because of >checkmate. You miss the point. It's not that all captures lead to checkmate, it's that you don't detect checkmates. Particularly, Amir was talking about a position with no captures out of check. If you don't try all legal moves, you don't know if you're checkmated. You can assume it if you want, but I don't think that the probability of capturing the checking piece, or capturing something to go out of check, is bigger than 0.50 for all in-check positions, thus you're gonna make more than 50% mistakes. José C. >You do not analyze quiet moves but there is a significant probability that quite >moves also cannot save you from checkmate. > >If you return static evaluation then you do not use important information and it >may be more logical to return something lower than the static evaluation >that considers the probability that you can do nothing against the checkmate >threat. > >Uri
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