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Subject: Maybe I understand better now ....

Author: John Coffey

Date: 17:02:42 09/28/98

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Looking at my copies of old threads maybe I understand better...


Just because you're behind in material at a node, doesn't mean you
won't regain (some of) it in the search below that node.  Let's
imagine that at a node you are behind in material, but are just about
to deliver mate, and your opponent can't get out of it--even if he's
given two moves in a row.  The null move will return the mate score
and give you an instant cutoff.  Or imagine the oppenent can
get out of it with those two moves, but only at the loss of a lot
of material.  Again you might get a cutoff.

The null move works as long as the score returned by the null move
search is greater than or equal to beta.  What the current material
is is...immaterial.

-Dan.


>>>>I try them _everywhere_ in the search, before trying any other move.  The idea
>>>>is that if your opponent can't take two moves in a row and crush you, your
>>>>position is **overwhelming** and doesn't need any further searching to prove that
>>>>it is probably winning...




...... so even if we are behind in material, a null move search that gives
my the opposite side two moves in a row could still produce a positive
result?  I.e. I was a rook down, but null move analysis shows that I am
only a pawn down, chances are I am really crushing the opponent?   If so,
then does this return an evalation that we can use in the tree?

John Coffey



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