2 research outputs found
Ensuring Liveness Properties of Distributed Systems (A Research Agenda)
Often fairness assumptions need to be made in order to establish liveness
properties of distributed systems, but in many situations these lead to false
conclusions.
This document presents a research agenda aiming at laying the foundations of
a theory of concurrency that is equipped to ensure liveness properties of
distributed systems without making fairness assumptions. This theory will
encompass process algebra, temporal logic and semantic models, as well as
treatments of real-time. The agenda also includes developing a methodology that
allows successful application of this theory to the specification, analysis and
verification of realistic distributed systems, including routing protocols for
wireless networks.
Contemporary process algebras and temporal logics fail to make distinctions
between systems of which one has a crucial liveness property and the other does
not, at least when assuming justness, a strong progress property, but not
assuming fairness. Setting up an alternative framework involves giving up on
identifying strongly bisimilar systems, inventing new induction principles,
developing new axiomatic bases for process algebras and new congruence formats
for operational semantics, and creating new treatments of time and probability.
Even simple systems like fair schedulers or mutual exclusion protocols cannot
be accurately specified in standard process algebras (or Petri nets) in the
absence of fairness assumptions. Hence the work involves the study of adequate
language or model extensions, and their expressive power
Reward Testing Equivalences for Processes
May and must testing were introduced by De Nicola and Hennessy to define
semantic equivalences on processes. May-testing equivalence exactly captures
safety properties, and must-testing equivalence liveness properties. This paper
proposes reward testing and shows that the resulting semantic equivalence also
captures conditional liveness properties. It is strictly finer than both the
may- and must-testing equivalence.Comment: This paper is dedicated to Rocco De Nicola, on the occasion of his
65th birthday. Rocco's work has been a source of inspiration to my ow