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Subject: Re: gnu chess scoring method

Author: Dann Corbit

Date: 13:25:15 01/14/03

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On January 14, 2003 at 16:10:10, marc efensy wrote:

>Do anyone know the evaluation function and mathematic equation if i want to make
>chess using minimax? (how to get the value to each node for 1 or 2 level) Is gnu
>using minimax? And how we implement minimax in program?

Nobody uses straight minimax.  It's unfathomably lame.  They use Alpha-Beta
cutoff, which examines [assuming excellent move ordering] sqrt(nodes) that
minimax alone would scour.

>Do anyone know how to calculate the final score in gnu chess ver 1.0? Example:
>if we move pawn a2 to a3 in first move, the gnu calculate the score -5. Where
>that -5 came from? How the can we evaluate that score by manual? not by compute
>it (for firsy move only)?

GnuChess 3.1 is the oldest copy that I have.

>I want to know what is the mathematic function. Ex: (sum all value
>black) - (sum all value white)? I only want to know the
>function and value for 1 depth (20 first possible move).

It's a lot smarter than just counting up the wood.  Look at the eval function.

Look here:
http://www.cs.mcgill.ca/~cs251/OldCourses/1997/topic11/
http://students.cs.byu.edu/~cs670ta/Lectures/Minimax.html
http://www.maths.nott.ac.uk/personal/anw/G13GT1/alphabet.html
http://www.cs.unca.edu/~bruce/Spring98/csci373/ch5/game-lecture.html
http://cindy.cis.nctu.edu.tw/AI/ai1/ai-6.htm

That should be enough to get you started.

Bruce Moreland, Colin Frayn, and James Swafford have excellent chess tutorials.
A web search will find them.



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