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Subject: Re: mate threat extension/null move

Author: Gerd Isenberg

Date: 12:49:00 10/05/04

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On October 05, 2004 at 05:57:36, Don Beal wrote:

>>by this:
>>    // test for null move prune
>>    value = -search(bd,sdepth-1-reduction,ply,-beta,-beta+1,
>>	mvstr,SAVETOP,verify,REDUCENOTOK,checked) + WACBOOST;
>>where WACBOOST is a bias that increases tactical prunes.
>
>Correction to my last post.  That should have been:
>
>  value = -search(bd,sdepth-1-reduction,ply,-beta+WACBOOST,-beta+1+WACBOOST,
>	mvstr,SAVETOP,verify,REDUCENOTOK,checked) + WACBOOST;

Hi Don,

a really nice lever to tune on tactial positions.
New to me and interesting - thanks for sharing!

Moving twice in a row but only archiving a small positional improvement
considers first move already bad enough to prune it - hmmm.
I guess during game play it is also worth to lose some extra games due to poor
positional play and seeing tactics against itself a bit earlier ;-)

What about keeping WACBOOST variable, probably initialized by evaluation or some
eval related heuristics to determine some metric of tactical aspects for both
sides, like en-prised pieces, hanging pieces, pins, possible checks, forks, king
safety, weak as well as passed pawns, etc?

Cheers,
Gerd



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