Computer Chess Club Archives




Subject: Null move idea

Author: Heiner Marxen

Date: 11:22:24 06/04/99

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?


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