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Subject: Re: Null Moves at the Root?

Author: Gian-Carlo Pascutto

Date: 11:31:57 12/23/00

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On December 23, 2000 at 12:53:03, Robert Hyatt wrote:

>
>I don't know if that would work.  Such a null-move search _must_ fail high,
>or else you are winning.  Because you just let the opponent play two moves in
>a row, and if he can't win with that advantage, something is up.  I don't think
>you can use the score returned by null-move to set the initial aspiration
>window for that reason.

I wasn't thinking of that, but of the case where two moves for the
opponent would not allow him to get his score high enough to stay
inside the window you originally set. In that case your window must
be way too high/low (depening on who's side you look at ;) or you
have a zugzwang situtation.

But now that you mention it, why not use the nullmove score as a lower
bound (alpha) for the search? The idea being that we must be able to
improve upon what would happen if we would pass. This might come in
handy in cases where you fail low, and instead of going to -INF, just
set alpha to the nullmove score.

--
GCP



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