Henri Korver

A correctness proof of the bakery protocol in

A specification of a bakery protocol is given in

\mu

\mu

CRL

CRL. We provide a simple correctness criterion for the protocol. Then the protocol is proven correct using a proof system that has been developed for

Formal verification of a leader election protocol in process algebra

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A Computer-Checked Verification of Milner's Scheduler

CRL. The proof primarily consists of algebraic manipulations based on specifications of abstract data types and elementary rules and axioms from process algebra.

Computing Distinguishing Formulas for Branching Bisimulation

In 1982 Dolev, et al. [10] presented an O(nlogn) unidirectional distributed algorithm for the circular extrema-finding (or leader-election) problem. At the same time Peterson came up with a nearly identical solution. In this paper, we bring the correctness of this algorithm to a completely formal level. This relatively small protocol, which can be described on half a page, requires a rather involved proof for guaranteeing that it behaves well in all possible circumstances. To our knowledge, this is one of the more advanced case-studies in formal verification based on process algebra.

A Formal Axiomatization for Alphabet Reasoning with Parametrized Processes

We present an equational verification of Milners scheduler, which we checked by computer.To our knowledge this is the first time that the scheduler is proof-checked for a general number n of scheduled processes.

Example Verifications Using Alphabet Axioms

Branching bisimulation is a behavioral equivalence on labeled transition systems which has been proposed by Van Glabbeek and Weijland as an alternative to Milners observation equivalence. This paper presents an algorithm which, given two branching bisimulation inequivalent finite state processes, produces a distinguishing formula in Hennessy-Milner logic extended with an ‘until’ operator. The algorithm, which is a modification of an algorithm due to Cleaveland, works in conjunction with a partition-refinement algorithm for deciding branching bisimulation equivalence. Our algorithm provides a useful extension to the algorithm for deciding equivalence because it tells a user why certain finite state systems are inequivalent.

A correctness proof of the bakery protocol in

Abstract.In the process-algebraic verification of systems with three or more components put in parallel, alphabet axioms are considered to be useful. These are rules that exploit the information about the alphabets of the processes involved. The alphabet of a process is the set of actions it can perform. In this paper, we extend μCRL (a formal proof system for ACPτ + data) with such axioms. The alphabet axioms that are added to the proof theory are completely formal and therefore highly suited for computer-checked verification. This is new compared to previous papers where the formulation of alphabet axioms relies for a considerable amount on informal data parameters and implicit (infinite) set theory.

mu

Abstract. This paper is supplementary to [KoS98]. It illustrates by means of examples the use of alphabet axioms as presented in [KoS98]. Furthermore a brief overview of μCRL [GrP94] and its proof theory [GrP93] are added.