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Subject: Question on Null Moves

Author: William Bryant

Date: 18:17:29 10/18/99


I may not ask this question right, so allow me the luxury of a long winded
question to try and explain the question completely.

When starting a new iteration, the PV holds the best moves searched to the depth
of n-1 (the previous depth).  These moves form the far left (or far right?) of
the search tree and make the first moves searched.  Now the question, since
these moves have already been searched, is there any point in stopping along the
way and doing a null move until this line has been extended initially to the new
depth.  IE the first leaf evaluated should be at the end of the old pv, should
it not.

My Null move code starts checking null moves while depth is sufficient.
Therefore, it will start null moves as soon as the first few moves of the pv
have been made on the way to the first leaf.  I empirically think that this will
simply waste time because this line has already been searched, and that null
moves should be postponed until after the first leaf has been searched or until
the tree has been extended initially down the first branch following the pv to
it's first.

Am I close?  Is there any advantage in doing the null moves while still
following the pv to the first leaf?

William
wbryant@ix.netcom.com

//my code idea goes like this

if (pv_move)
	do_Null = false;

pv_move is set to false as soon as search at any iteration moves beyond the
bestmove phase and generates moves for the ply.




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