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Subject: Move ordering

Author: Scott Gasch

Date: 16:36:18 11/27/00


Hi,

I recently attempted to change my move ordering so that "losing" captures
(MVV/LVA) were searched after everything else.  This resulted in search trees
about 30% larger than when I searched all captures at once, best to worst
(MVV/LVA) before any non-capture moves.

The reason I tried this was because both Prof. Hyatt and an article online by E.
Heinz suggest losing captures should be tried last for better move ordering.
Does this rule hold if I am doing a simple MVV/LVA move value scheme instead of
a more complicated SEE?  How can I be sure a capture is "losing" just because
the piece I capture with is more valueable than the captured piece?

Should qxn when n is hung be search last in a position just because it's
considered "losing" since the queen > knight?  This seems wrong to me because
most likely such a hung-knight position would be a beta cutoff and we could have
saved all the work of considering all other non-capture moves in this position
had we looked at this "losing" capture first.  IS this just the exception to the
rule?  Don't get me wrong, I'm all for apparently "better" captures before
"worse" ones but I wonder if I am misunderstanding where to search the "worse"
capture moves.  It would seem to be so since my tree expands after I make this
change.

Scott



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