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Subject: Re: Thanks Dann! But the question is still...

Author: Dann Corbit

Date: 09:30:55 06/03/02

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On June 01, 2002 at 09:15:12, Omid David wrote:

>The question was an algorithmic one: How to escape a full window search of
>(-10000,10000) at any cost. In theory this shouldn't occur since after the
>following steps:
>
>best = negascout(alpha, beta, depth);
>/* re-search */
>if(best <= alpha)
>        best = AlphaBeta(-10000, beta, depth);
>else if(best >= beta)
>        best = AlphaBeta(alpha, 10000, depth);
>
>The value should be between the alpha-beta bound. However in practice sometimes
>it happens that after the re-search the result is still out of the bound. The
>frequency of this depends on the evaluation function. While Genesis faces this
>problem very rarely, other programs with simpler eval functions will more
>frequently have to deal with the problem above.
>
>In none of the open-source programs I found an algorithmic solution to the
>problem. Maybe this is the way it has to be!
>
>And, thanks Dann for all the code you posted, it saved me hours of navigation in
>different programs' codes!

I think pretty much everyone does the same thing.
After all, the search failed.  You have to find the right score.



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