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

Author: Ryan B.

Date: 14:56:42 03/01/06

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On March 01, 2006 at 05:25:38, Vasik Rajlich wrote:

>On February 28, 2006 at 08:22:54, John Sidles wrote:
>
>>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
>
>Are you daring to question minimax? :)
>
>Vas


Some people pick the search tree that looks like a rectangle. Some people pick
the search tree that looks like a triangle.  However just like the little wooden
blocks I used to play with the hole is a circle and there is no circle block to
put in the hole (I still think someone took it to be mean!) I guess the triangle
will have to work for now.  The rectangle is far too much work to get in the
hole and takes far too long.

Ryan



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