Bidirectional inference of mode information for logic programs

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Abstract

Mode information (directional information concerning the arguments of predicates) is important in improving the speed of the execution of logic programs. This paper proposes a bidirectional inference algorithm for inferring precise mode information. Compared with the conventional inference algorithms, the proposed algorithm has the following two features: (1) the algorithm utilizes not only the modes of the predicates at the top level but also the modes of the built-in predicates used in the program; and (2) by propagating the modes of the top level predicates top-down and that of the built-in predicates bottom-up, more precise mode information can be inferred.

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