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Subject: Re: Opinions requested -- what to do when qsearch ends in checkmate...

Author: Uri Blass

Date: 05:10:47 07/25/03

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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 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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