Discrete Mathematics & Theoretical Computer Science


Volume 1 n° 1 (1997), pp. 69-98

author:Sébastien Limet and Pierre Réty
title:E-unification by means of tree tuple synchronized grammars
keywords:E-unification, narrowing, tree languages, decidability
abstract:The goal of this paper is both to give an E-unification procedure that always terminates, and to decide unifiability. For this, we assume that the equational theory is specified by a confluent and constructor-based rewrite system, and that four additional restrictions are satisfied. We give a procedure that represents the (possibly infinite) set of solutions thanks to a tree tuple synchronized grammar, and that can decide upon unifiability thanks to an emptiness test. Moreover, we show that if only three of the four additional restrictions are satisfied then unifiability is undecidable.
reference: Sébastien Limet and Pierre Réty (1997), E-unification by means of tree tuple synchronized grammars, Discrete Mathematics and Theoretical Computer Science 1, pp. 69-98
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