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Subject: Re: Selectivity for long time controls.

Author: José de Jesús García Ruvalcaba

Date: 14:21:48 07/30/99

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On July 30, 1999 at 16:08:44, blass uri wrote:

>
>On July 30, 1999 at 14:05:01, José de Jesús García Ruvalcaba wrote:
>
>>	A few weeks ago somebody asked which selectivity levels were better for CM6000
>>to analyze at very long time controls, suited for correspondence play.
>>	The advice given was to use zero selectivity. I do not remember why I did not
>>answer at that time, but my advice is exactly the opposite: the longer the time
>>control the higher the selectiviyy level should be set, and not only for CM6000
>>but for any program that allows you to change it.
>>	The reason is that, due to the exponential nature of the search tree, the extra
>>time is almost worthless when using no selectivity or very low selectivity.
>>Jos
>
>It depends on the program.
>

	Yes. I was trying to state the general tendency that higher selectivity is
better for longer time controls.

>I know that previous version of Rebel were more selective and it cause a problem
>because Rebel prune some good moves with the selectivity.
>

	Any selectivity can (and will) prune some good moves. But the risk should be
minized at longer time controls.

>If you use high selectivity (do not analyze moves that you consider as illogical
>moves) then you can miss simple tactics because you prune some good sacrifices
>and do not analyze them and it may be a big problem at long time controls.
>

	I think that kind of selectivity (not analyzing "illogical" moves) is not used
since the late seventies. I meant selectivity that analyzes moves with poor
scores less deeply than moves with good scores.

>Uri
José.



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