Abstract

. An unfold/fold program transformation system which extends the unfold/fold transformations of H. Tamaki and T. Sato is presented in this paper. The system consists of unfolding, simultaneous folding, and generalization + equality introduction rules. The simultaneous folding rule permits the folding of a set of folded clauses into a single clause, using a set of folding clauses, while the generalization + equality introduction rule facilitates the application of the simultaneous folding rule by performing appropriate abstractions. A proof of the correctness of the proposed transformations in the sense of the least Herbrand model semantics of the program is also presented. 1 Introduction Unfold/fold transformations were first proposed by R. Burstall and J. Darlington [BD77] in the context of a functional language. In the context of logic programming, H. Tamaki and T. Sato [TS84, TS86] formulated unfold/fold transformations for definite clause programs so as to preserve the equivalence...

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