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Subject: Re: Quiescence search - checking & check evasion moves and Hsu

Author: Robert Hyatt

Date: 11:15:05 04/11/02

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On April 11, 2002 at 12:55:45, Gian-Carlo Pascutto wrote:

>On April 11, 2002 at 04:32:02, Bas Hamstra wrote:
>
>>Sounds reasonable. However I saw you complain many times about nullmove hiding
>>many mate threats. Well, that IS related. With such a mini qsearch you create
>>dangerous blind spots. Question is are you willing to sacrifice a little
>>positional depth to get rid of those blind spots. Personally I am.
>
>I agree with your assesement, but whenever I tried checks in
>qsearch, my search blew up. Even if I limited them in all kinds
>of ways, the branching factor got out of hand. It already is
>somewhat large, so I couldn't allow it to get bigger.
>
>I wonder if you 'try' checks (have a few rules that indicate
>when it might be worth trying certain moves) or 'filter' checks
>(have rules when a check is prolly bad) or do something
>even different.
>
>Because I couldn't get it to work in qsearch, I've been trying
>to make the evaluation catch those blind spots. So far, it helps
>againt the biggest problems, but still...
>
>--
>GCP


there are ideas such as those I gave here years ago when describing what we did
in Cray Blitz.

One good limit is that before looking at checks at the current q-search node,
confirm that we checked the opponent at _every_ q-search node in this path,
so that he has no option to stand-pat.  If he can stand pat, then finding
forced mates against him beyond that won't pass that mate score back beyond
the stand-pat node.

That limits the checks to an extent because if the first q-search move for this
side is a non-check, then no checks will ever be looked at deeper in the
q-search.

You can also look to see if there were any checks in the basic search.  If not,
is it worth looking at checks in the q-search as well?

Other ideas will probably limit it farther, but we did at least the above two
in Cray Blitz.  I'll try to look to see what else we did...



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