Computer-Assisted Verification of an Algorithm for Concurrent Timestamps

A formal representation and machine-checked proof are given for the Bounded Concurrent Timestamp (BCTS) algorithm of Dolev and Shavit. The proof uses invariant assertions and a forward simulation mapping to a corresponding Unbounded Concurrent Timestamp (UCTS) algorithm, following a strategy developed by Gawlick, Lynch, and Shavit. The proof was produced interactively, using the Larch Prover. Keywords Verification, validation and testing; tools and tool support; Larch; input/output automata; concurrent timestamps 1 INTRODUCTION In this paper, we describe a computer-assisted verification, using the Larch Prover (Garland and Guttag, 1991), of one of the most complicated algorithms in the distributed systems theory literature: the Bounded Concurrent Timestamp (BCTS) algorithm of Dolev and Shavit (1989). This algorithm runs in the single-writer, multi-reader, read/write shared memory model. The verified algorithm is a slight simplification, due to Gawlick, Lynch, and Shavit (1992), of t..

Compositional reasoning for probabilistic finite-state behaviors

Abstract. We study a process algebra which combines both nondeterministic and probabilistic behavior in the style of Segala and Lynch’s simple probabilistic automata. We consider strong bisimulation and observational equivalence, and provide complete axiomatizations for a language that includes a restricted form of parallel composition and (guarded) recursion. The presence of the parallel composition, in particular, introduces various technical difficulties, but we believe that a “good ” compositional semantics should take it into account since it is an essential operator to specify concurrent systems.

La notion d'employeur pour la détermination de la législation de sécurité sociale applicable à des chauffeurs routiers internationaux : ou l'impossibilité pour les entreprises de faire usage de montages purement artificiels afin d'utiliser la réglementation de l'Union dans le seul but de tirer avant

La notion d’employeur pour la détermination de la législation de sécurité sociale applicable à des chauffeurs routiers internationaux : ou l’impossibilité pour les entreprises de faire usage de montages purement artificiels afin d’utiliser la réglementation de l’Union dans le seul but de tirer avantage des différences existant entre les régime