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Subject: Re: SEE (was extensions)

Author: Robert Hyatt

Date: 12:07:36 12/29/97

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On December 29, 1997 at 14:37:53, Stuart Cracraft wrote:

>On December 28, 1997 at 13:30:31, Robert Hyatt wrote:
>
>>On December 28, 1997 at 11:47:20, Stuart Cracraft wrote:
>>
>>>What is SEE? Some canned knowledge routine?
>>
>>Static Exchange Evaluator...  a procedure that looks at all possible
>>captures on a specific square and returns a score based on the expected
>>gain (or loss) of initiating the first move of the exchange sequence...
>>
>>used to order captures for one thing...  and to cull outrageously
>>losing captures for another...
>
>How much increase in quiescence-search (and overall search) efficiency
>does this provide? Or speedup for that matter.
>
>Is your SEE routine written in a way that it would be simple to
>rewrite/convert
>for another program?
>
>Which of the Crafty modules is it actually in?
>
>Thanks,
>Stuart


It is in swap.c...

It can speed up the search by a factor of 2 or 3, assuming you aren't
doing anything "good" about ordering your capture search yet.  If you
apply SEE to each capture, sort based on the score returned, the tree
will shrink.  If you toss out captures (in the q-search) where SEE
returns a score < 0, you will get another big reduction...  and if you
use the SEE score to defer losing captures until after winning captures,
hash move, even exchanges, history and killer moves, you will save even
more time...



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