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Subject: Re: NULL MOVE

Author: Will Singleton

Date: 18:52:21 02/24/99

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On February 24, 1999 at 15:53:49, Don Dailey wrote:

>Your statement about not using two null moves in row shouldn't matter.
>I had this rule in my program and Don Beal asked me, "why?"  I took
>it out and the program worked fine.   I think a few years ago
>my implementation of null move needed this rule to prevent infinite
>recursion, but I cannot remember for the life of me why this was so.
>The worst that can happen is that you do more  depth reduced
>searches which is such a tiny fraction of the whole you will not be
>able to measure the difference in time.   But even this won't happen
>if you do not do a null move search when the "stand pat" score is
>already below beta.  Some programs do the null move selectivity anyway,
>or they do it if the score is CLOSE to beta.  However I decided to
>ignore any minor speedups this gave because it also introduces
>some risk.  I really doubt you can prove one is better than the
>other and my current program doesn't even register a speedup for
>- Don

Two nulls in a row??  I don't understand that.  How could either side move at
all if you have consecutive null moves?  Or maybe you mean multiple nulls along
the same branch?


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