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Subject: Re: Exact value of second best move in AlphaBeta with aspiration Window

Author: Robert Hyatt

Date: 20:21:30 08/01/02

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On August 01, 2002 at 17:45:33, Dieter Buerssner wrote:

>On August 01, 2002 at 09:32:08, Robert Hyatt wrote:
>
>>On August 01, 2002 at 04:50:23, Martin Bauer wrote:
>>
>>>Hello all,
>>>
>>>In want to detect position at the root node, where the best move is _much_
>>>better then all other moves. For Example, only 1 possibility for recapture the
>>>quenn.
>>
>>
>>Simple solution.  Search the recapture with the window (X,Y).  Search
>>the _other_ moves with the window (X-q, Y-q) where q is some large
>>constant (say 2.00).  If the best move is q better than the others,
>>the others will _still_ fail low.  If one is within q of the best move,
>>it will fail high...
>
>I cannot totally follow here. After searching "the recapture with the window
>(X,Y)", you get back a score s. I would then search the other moves with the
>window(s-q, s-q+1).

In your example above, X=s, Y=s+1.  The offset is simply Q, as I said...

:)




>
>>Then you have to re-search with a different window, which will cost a lot of
>>time...
>>
>
>If you get a fail high here - why research? You already know that it is not an
>"easy move".

You _still_ need a score for the move.  Particularly if two of the moves fail
high, so that you can choose between them...



>
>Regards,
>Dieter



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