DFKI Research Report-92-22

[Back]

RR-92-22



Language: English

by Jörg Würtz

Unifying Cycles

24 Pages

Abstract

Two-literal clauses of the form L leftarrow R occur quite frequently in logic programs, deductive databases, and--disguised as an equation--in term rewriting systems. These clauses define a cycle if the atoms L and R are weakly unifiable, i.e., if L unifies 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 unification problem of unifying two literals G and F modulo a cycle. We review the state of the art of cycle unification and give new results for a special type of cycles called unifying cycles, i.e., cycles L leftarrow R for which there exists a substitution sigma such that sigmaL = sigmaR. Altogether, these results show how the deductive process can be efficiently controlled for special classes of cycles without losing completeness.

This document is available as PDF-File(18,6MB).

The next abstract is here, and the previous abstract is here.

DFKI-Bibliothek (bib@dfki.uni-kl.de)

Note: This page was written to look best with CSS stylesheet support Level 1 or higher. Since you can see this, your browser obviously doesn't support CSS, or you have turned it off. We highly recommend you use a browser that supports and uses CSS, and review this page once you do. However, don't fear, we've tried to write this page to still work and be readable without CSS.