The Topos of Labelled Trees: A Categorical Semantics for SCCS

  • Authors:
  • Stefano Kasangian;Sebastiano Vigna

  • Affiliations:
  • Dipartimento di Scienze dell'Informazione Università Ca' Foscari di Venezia Venezia, Italy kasan@vmimat.mat.unimi.it;Dipartimento di Scienze dell'Informazione Università degli Studi di Milano Milano, Italy vigna@dsi.unimi.it

  • Venue:
  • Fundamenta Informaticae
  • Year:
  • 1997

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Abstract

In this paper a we give a semantics for SCCS using the constructions of the topos of labelled trees. The semantics accounts for all aspects of the original formulation of SCCS, including unbounded non-determinism. Then, a partial solution to the problem of characterizing bisimulation in terms of a class of morphisms is proposed. We define a class of morphisms of the topos of trees, called conflict preserving, such that two trees T and U are bisimilar iff there is a pair of conflict preserving morphisms f : T → U and g : U → T such that fgf = f and gfg = g. It is the first characterization which does not require the existence of a third quotient object. The results can be easily extended to more general transition systems.