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Subject: Re: Evaluate function in Alpha-beta search?

Author: Robert Hyatt

Date: 15:17:06 10/22/03

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On October 22, 2003 at 17:07:13, Gopi wrote:

>In min-max search, evaluate function returns score with respect to white.Is
>evaluate function similar in alpha-beta search also or does it return score with
>respect to side that is moving? Thanks.


minimax is one way, with scores relative to white.  negamax is a simpler
way to program minimax, and there the scores are relative to the side on
move.  Both produce the same best move, same best score, etc.

Alpha/beta is just an enhancement to minimax or negamax that reduces
the size of the tree without reducing the accuracy.  If you write a pure
minimax search, you can add alpha/beta, and it will work just fine with
an evaluation that returns scores +=good for white.  If you write a
negamax search, and add alpha/beta, you want scores +=good for side on move.




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