Local and temporal predicates in distributed systems

  • Authors:
  • Bernadette Charron-Bost;Carole Delporte-Gallet;Hugues Fauconnier

  • Affiliations:
  • Ecole Polytechnique;Université Paris 7;Université Paris 7

  • Venue:
  • ACM Transactions on Programming Languages and Systems (TOPLAS)
  • Year:
  • 1995

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Abstract

The definitions of the predicates Possibly &fgr; and Definitely &fgr;, where &fgr; is a global predicate of a distributed computation, lead to the definitions of two predicate transformers P and D. We show that P plays the same role with respect to time as the predicate transformers Ki in knowledge theory play with respect to space. Pursuing this analogy, we prove that local predicates are exactly the fixed points of the Ki's while the stable predicates are the fixed points of P. In terms of the predicate transformers P and D, we define a new class of predicates that we call observer-independent predicates and for which the detection of Possibly &fgr; and Definitely &fgr; is quite easy. Finally, we establish a temporal counterpart to the knowledge change theorem of Chandy and Misra which formally proves that the global view of a distributed system provided by its various observations does not differ too much from its truth behavior.