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Subject: Re: What's the Secret to Shredder 7.04 Success?

Author: Dieter Buerssner

Date: 14:41:30 05/04/03

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I snipped all the context. I just wanted to give some additional possibly
interesting thoughts.

First of all, the following papers of Ernst Heinz might be an interesting
reading for the parties involved or interested in this discussion:

E.A. Heinz.
Knowledgeable encoding and querying of endgame databases.
In ICCA Journal, Vol. 22, No. 2, pages 81-97, June 1999.
(published by the ICCA; preprint available from
http://supertech.lcs.mit.edu/~heinz/ps/know_edb.ps.gz)

E.A. Heinz.
Efficient interior-node recognition.
In ICCA Journal, Vol. 21, No. 3, pages 156-167, September 1998.
(published by the ICCA; preprint available from
http://supertech.lcs.mit.edu/~heinz/ps/node_rcg.ps.gz)

I agree with Uri, that there are many cases, where one can avoid the (time
overhead induced by) TB-probing. For example almost all 4 vs. 1 TBs would fit
this. But, one really has to be careful. I think, knowledge, that is correct in
only 99% of the cases will hurt here. Sooner or late the opponent will find the
hole in your knowledge (I have seen practical cases, where engines lost because
of seemingly clever knowledge, that did not apply exactly, while a stupid engine
would have easily reached a draw, even without any understanding/knowledge of
the position).

TBs can help, to design perfect knowledge. One can test the "knowledge function"
vs. the perfect knowledge of TBs, and find any exception. I did this for the
latest version of Yace, for some easy positions with 4-men. For example N vs. P.
Typically, the N cannot win, but sometimes it can (when the P is a rook P and
the K is in a bad pos). With some rechecking against TBs, it was not difficult,
to find rules, that include all exceptions. Note, that this does not mean, that
the engine can statically evaluate all positions correctly. But it can delay
pruning, which will be enough in many cases (and will be not worse, than not
trying to "apply" the knowledge anyway).

There are quite a few other subtle points, that can be considered here. Recently
an interesting position was shown in this forum, where a TB equipped engine
refused to take a pawn in KPPPKR, and thereby lost. Similar other scenarios are
possible.

Regards,
Dieter






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