Tree-Searching and Tree-Pruning Techniques
This paper first discusses the now standard tree searching techniques of mini-max and alpha-beta and the recent improvements to alpha-beta, in particular the killer heuristic. It then describes a new and very powerful technique that we have termed ‘razoring’. Unlike the alpha-beta technique, razoring cannot guarantee finding the optimum solution but it will, however, always find a good solution in a much shorter time. Typically a four-ply tree with a branching factor of 33 can be searched an order of magnitude faster than with alpha-beta. We also discuss ‘forward marginal pruning’ — a technique similar to razoring.
KeywordsAtion Function Node Count Game Tree Node Evaluation Bottom Node
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