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Subject: Re: Programmers: beginner tree search questions

Author: Dave Gomboc

Date: 14:43:11 10/01/03

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On September 30, 2003 at 18:17:33, Dieter Buerssner wrote:

>On September 30, 2003 at 18:02:45, Gian-Carlo Pascutto wrote:
>
>>On September 30, 2003 at 17:37:27, Dieter Buerssner wrote:
>>
>>>On September 30, 2003 at 16:49:41, Gian-Carlo Pascutto wrote:
>>>
>>>>PVS = Negascout
>>>
>>>I don't think so. See http://www.zib.de/reinefeld/bib/83icca.pdf
>>>To me the unique thing about Negascout is to avoid those reasearches that
>>>initially returned scores out of bounds close to the leaf. Of course, I think
>>>that Negascout will not work in most chess engines (which use pruning,
>>>extensions, qsearch, etc.) but only in a fixed depth environment.
>>
>>For any practical implementation you have to drop the optimization
>>and they become identical.
>
>Indeed. And I see no reason to call it Negascout anymore then. I think PVS (with
>the main idea of the zero window searches) was introduced by Marsland. Reinefeld
>found (for fixed depth searches) that one can do better, and avoid the
>researches close to the leaves. Reinefeld called his algorithm Negascout.
>
>Perhaps, I got the history wrong here. I think, one should not call a PVS
>algorithm (with those zero window searches) Negascout, when one does not use the
>"optimization" introduced by Reinefeld. And of course, practically, that
>optimization is useless for most engines (I guess).
>
>Regards,
>Dieter

Well, we generally refer to it as PVS here.  But then, Tony Marsland is one of
my supervisors. ;-)

Dave



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