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Subject: Re: PV Search

Author: Alex Boby

Date: 09:44:51 04/21/99

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On April 21, 1999 at 03:42:58, Ulrich Tuerke wrote:

>On April 20, 1999 at 15:55:37, Alex Boby wrote:
>
>>
>>   Hey guys,... I think the intent of the Principle Variation Search is to
>>search it first and thus establish the best alpha/beta values for maximum
>>pruning.
>> What I don't understand is how to get the search to return a whole PV
>>instead of just the best move at ply 1. I currently just use full width
>>alpha/beta minimax and I think that adding PV would be a great improvement for
>>move ordering. Any help would be much appreciated.
>
>I think that PV search usually means something different: on each node, the 1st
>move of the current move list is searched with the usual alpha-beta aspiration
>window, the remaining moves are searched using a minimum window around beta.
>This will be sufficient to refute these moves unless one of these fails high;
>then a verification search must be performed.
>In general, this algorithm generates smaller trees. IMO in practice, there are
>also some draw-backs because of additional alpha beta dependences of the search.
>
>BTW, there are many articles about PV search, for instance the one by Donninger
>in the ICCA journal a few years ago, also giving pseudo code.
>
>Uli

   Are any of these articles available on the web?



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