Computer Chess Club Archives




Subject: Re: Null move idea

Author: José de Jesús García Ruvalcaba

Date: 11:51:19 06/04/99

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On June 04, 1999 at 14:22:24, Heiner Marxen wrote:

>While I agree that "null move" is a good thing, there is
>one disadvantage: it is sometimes wrong, especially in
>zugzwang positions.  This *can* be a problem, although rarely.
>I wonder whether this disadvantage can be corrected such,
>that the speed advantage is not given up, but at least
>at greater depths the error is detected/corrected.
>My idea: when doing a null move search with depth-R does
>produce a beta cutoff, (and depth-R is large enough,)
>verify the result by another search with depth-R-1 (say),
>with null move suppressed at the top of that search.
>The additional search is reduced in depth, again,
>and hence should not cost more than the null move search
>itself.  And to some extent we would now be more sure,
>that there really exists a legal move which is good
>enough.  And with more depth this would become more accurate.
>Is this possible?  Or meaningless?

	Some programs allow two consecutive null moves in the search (but not more),
which looks like your proposal for another search without null move at the top,
but with depth-2R instead of depth-R-1.

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