How Game-Playing Computers Think

Minimaxing assigns one player a positive value and the other a negative value. (In this case, the computer is player 1, the maximizer, and the human is player 2, the minimizer.) Once established, the values assigned each node can be judged as benefiting the maximizer (the "positive" player) or the minimizer (the "negative" player). Each node represents the positions of all the pieces after a move has been made--more generally, the state of the game at the moment. Alpha-beta pruning eliminates parts of the tree that are poor path choices relative to other pathways. For example, once the computer recognizes that it can win by moving to node c, it no longer needs to analyze any of its other options from node a.



Image: Meg Crane
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