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Subject: Re: YACE extensions?!?

Author: Dieter Buerssner

Date: 04:33:10 11/24/01

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On November 23, 2001 at 08:30:08, Steve Maughan wrote:

>I came across the YACE web site the other day (http://home1.stofanet.dk/Moq/).
>Interestingly it explains some of the search techniques employed by YACE.
>
>One that I haven't come across before is explained as follows:
>
>"ALL_MOVES_IN_CHECK: When set, and a capture checks the opponent, essentially
>one non capture search will be done. This will need a bit more time, but will
>find mates earlier."
>
>Any idea what's meant?  My guess is that when a capturing move also gives check
>extend the search.

More or less, yes. But as GCP has pointed out, this is not really and extension
(but similar). The idea of quiescent search is to reach a quiet position. This
is usually defined, as giving the player at move the choice to capture or not.
But one thing does not really fit inside here: when we are in check already,
this is not really quiet. But in deep qsearch, doing a lot of things may also
hurt the performance.

Anyway, by default, when the score looks promising (> alpha), and the side to
move is in check, Yace will not allow to return the positional evaluation, but
tries to do something about it. The default beheviour here again is to do an
almost normal search, after which a new qsearch is started. The
"ALL_MOVES_IN_CHECK" describes this. To me it is not clear, which of the
different stratagies works best, but the defaul values seem to be reasonable.

Regards,
Dieter




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