Calculating Invariants as Coreflexive Bisimulations

  • Authors:
  • Luís S. Barbosa;José N. Oliveira;Alexandra Silva

  • Affiliations:
  • CCTC, Universidade do Minho, Braga, Portugal 4700-320;CCTC, Universidade do Minho, Braga, Portugal 4700-320;Centrum voor Wiskunde en Informatica (CWI), Amsterdam, NL-1098 SJ

  • Venue:
  • AMAST 2008 Proceedings of the 12th international conference on Algebraic Methodology and Software Technology
  • Year:
  • 2008

Quantified Score

Hi-index 0.00

Visualization

Abstract

Invariants, bisimulations and assertions are the main ingredients of coalgebra theory applied to software systems. In this paper we reduce the first to a particular case of the second and show how both together pave the way to a theory of coalgebras which regards invariant predicates as types. An outcome of such a theory is a calculus of invariants' proof obligation discharge, a fragment of which is presented in the paper.The approach has two main ingredients: one is that of adopting relations as "first class citizens" in a pointfree reasoning style; the other lies on a synergy found between a relational construct, Reynolds' relation on functionsinvolved in the abstraction theoremon parametric polymorphism and the coalgebraic account of bisimulations and invariants. This leads to an elegant proof of the equivalence between two different definitions of bisimulation found in coalgebra literature (due to B. Jacobs and Aczel & Mendler, respectively) and to their instantiation to the classical Park-Milner definition popular in process algebra.