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Subject: Re: The number of nodes of critical trees?

Author: Ernst A. Heinz

Date: 09:22:31 11/01/00

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> On November 01, 2000 at 00:17:29, Robert Hyatt wrote:
>
>I should add that the quoted within 30% of optimal seems wrong.  I recall
>Hans Berliner doing a test like this and I believe he quoted 100%.  IE the
>searched tree was about twice as big as the optimal tree, which is _still_
>very good since we can't possibly have perfect move ordering.

I am sorry to say so, Bob, but you are _dead wrong_ here.

Ebeling and Berliner always mentioned 40% overhead for HITECH
as compared to the critical tree in their publications. See
page 102 in "Computers, Chess, and Cognition" for example.

Tony Marsland provides a nice comparison of the various search
and move-ordering enhancements with respect to the critical
tree in Figure 8 of "Computer Chess and Search" published in
the "Encyclopedia of AI (2nd ed.)". There we see 20% to 30%
overhead at depths of 2 to 6 plies for the combination of all
those enhancements (including PVS, best hashed move, and
history heuristic).

Last but not least, Rainer Feldmann mentions the 20% to 30%
overhead in his Ph.D. thesis about the sequential version of
ZUGZWANG.

I am really surprised that you do not seem to remember these
numbers because I am sure that you know the publications I
refer to above.

=Ernst=



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