Extending H1-clauses with path disequalities

  • Authors:
  • Helmut Seidl;Andreas Reuß

  • Affiliations:
  • Institut für Informatik I2, Technische Universität München, Garching, Germany;Institut für Informatik I2, Technische Universität München, Garching, Germany

  • Venue:
  • FOSSACS'12 Proceedings of the 15th international conference on Foundations of Software Science and Computational Structures
  • Year:
  • 2012

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Abstract

We extend H1-clauses with disequalities between paths. This extension allows conveniently to reason about freshness of keys or nonces, as well as about more intricate properties such as that a voter may deliver at most one vote. We show that the extended clauses can be normalized into an equivalent tree automaton with path disequalities and therefore conclude that satisfiability of conjunctive queries to predicates defined by such clauses is decidable.