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Subject: Chess strength without chess knowledge == Rybka ??

Author: John Sidles

Date: 05:22:54 02/28/06


Dear CCCers

I'm much more a "lurker" here than any kind of chess expert, but
I would be interested in learning from CCC's programming experts
mroe about how (if at all) chess programs evaluate, not the score
of the board, but the score of the move tree.

The point being that maybe Rybka's surprising strength comes not
from its knowledge of chess, but from a superior assessment of
the branching and topology of the move tree.

E.g., suppose white and black both look 15 moves ahead, and they
foresee that with optimal play, the board score will be roughly
equal. But even if the score is equal, if black's play is
essentially forced, while white's play has many strategic
options, then white has a huge advantage. In military language
white's advantage is called a "favorable strategic landscape".

So it is clearly important for any chess program to steer the
game so as to achieve a favorable strategic landscape. There are
at least two ways to do this. The first way is a highly tuned
evaluation function, i.e., knowledge that rooks have a higher
weight than knights.

The second, more subtle way, is achieved purely by examining the
branching and topology of the search tree, i.e., determining
whether the strategic landscape with a rook in it is more
favorable than the strategic landscape with a knight in it. This
latter technique, in principle, requires no chess knowledge.

A good program will use both methods. So I would be very
interested to learn more about how chess program authors assess
their search tree.

SIncerely ... John Sidles



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