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Subject: Re: search instability?

Author: Tony Werten

Date: 08:43:23 12/06/03

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On December 06, 2003 at 04:05:24, Daniel Shawul wrote:

>hi
>
>here is my PVS code
>
>   if(first move)
>       score=-search(-beta,-alpha,depth-1);
>   else
>   {
>       score=-search(-alpha-1,-alpha,depth-1);
>       if(score>alpha && score<beta)
>          score=-search(-score,-alpha,depth-1);
>   }
>
>should i use (-beta,-alpha) when search fails instead of (-score,-alpha).
>can the algorithm handle search instablity correctly?

You should either use (-beta,-score ) or (-beta,-previous_best_score) or even
(-beta,-alpha).

The second one gives the search to change to solve a false fail high, the third
is a bit overdone.

Either way, your (-score,-alpha) is wrong.

Tony

>
>regards
>daniel



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