Unification in combinations of collapse-free theories with disjoint sets of function symbols

  • Erik Tidén
Unification Theory
Part of the Lecture Notes in Computer Science book series (LNCS, volume 230)


A unification algorithm for combinations of collapse-free equational theories with disjoint sets of function symbols is presented. The algorithm uses complete unification algorithms for the theories in the combination to compute complete sets of unifiers in the combined theory. It terminates if the algorithms for the theories in the combination terminate. The only restriction on the theories in the combination — apart from disjointness of function symbol sets — is that they must be collapse-free (i.e., they must not have axioms of the form t=x, where t is a non-variable term and x is a variable). This extends the class of equational theories for which the unification problem in combinations can be solved to collapse-free theories. The algorithm is based on a study of the properties of unifiers in combination of non-regular collapse-free theories.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1986

Authors and Affiliations

  • Erik Tidén
    • 1
  1. 1.Department of Computing ScienceRoyal Institute of TechnologyStockholm

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