It has been accepted that the techniques of hierarchical problem solving can improve the efficiency of problem solving and theorem proving system. One of important problems in hierarchical problem solving is the automatic formation of the abstraction hierarchies. Some approaches have been proposed to form automatically the abstraction hierarchies for planning system. However, these approaches can not be applied to theorem proving system, since they are built on the planning systems based on the representation of STRIPS-like operators. In this paper we propose an approach to automatic formation of the abstraction hierarchies of theorem proving based on a definitional hierarchy. In this approach, each abstraction hierarchical level is assigned to a value based on the definitional hierarchy and the theorem to prove. A predicate will be supposed to be provable if the rank of the predicate in the definitional hierarchy is smaller than the value of the abstraction hierarchy. It is useful for the domains with a great amount of definitions such as mathematics. Contradiction may occur in the abstract theory generated by abstraction. To solve this problem a procedure of generating a consistent abstract theory by using propositional abstraction is proposed. This approach is implemented on a knowledge based theorem proving system in which axioms, definitions and theorems are represented as production rules. Some results of the experiment on topological space are investigated.
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