Cycle Uniication
نویسنده
چکیده
Two-literal clauses of the form L R occur quite frequently in logic programs, deductive databases, and { disguised as an equation { in term rewriting systems. These clauses deene a cycle if the atoms L and R are weakly uniiable, ie. if L uniies with a new variant of R. The obvious problem with cycles is to control the number of iterations through the cycle. In this paper we consider the cycle uniication problem of unifying two literals G and F modulo a cycle. We review the state of the art of cycle uniication and give some new results for a special type of cycles called matching cycles, ie. cycles LR for which there exists a substitution such that L = R or L = R. Altogether, these results show how the deductive process can be eeciently controlled for special classes of cycles without losing completeness.
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Syntacticness, Cycle-Syntacticness, and Shallow Theories
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