ACID-Unification Is NEXPTIME-Decidable

  • Siva Anantharaman
  • Paliath Narendran
  • Michael Rusinowitch
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2747)


We consider the unification problem for the equational theory AC(U)ID obtained by adjoining a binary ‘*’ which is distributive over an associative-commutative idempotent operator ‘+’, possibly admitting a unit element U. We formulate the problem as a particular class of set constraints, and propose a method for solving it by using the dag automata introduced by W. Charatonik, that we enrich with labels for our purposes. AC(U)ID-unification is thus shown to be in NEXPTIME.


E-Unification Complexity Set constraints Tree automata Dag automata 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Siva Anantharaman
    • 1
  • Paliath Narendran
    • 2
  • Michael Rusinowitch
    • 3
  1. 1.LIFO – OrléansFrance
  2. 2.University at Albany–SUNYUSA
  3. 3.LORIANancyFrance

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