Synthesizing Distinguishing Formulae for Real Time Systems

This paper describes a technique for generating diagnostic information for the timed bisimulation equivalence and the timed simulation preorder. More precisely, given two (parallel) networks of regular real-time processes, the technique will provide a logical formula that differentiates them in case they are not timed (bi)similar. Our method may be seen as an extension of the algorithm by Cerans for deciding timed bisimilarity in that information of time-quantities has been added sufficient for generating distinguishing formulae. The technique has been added to the automatic verification tool EPSILON and applied to various examples

TPAP An algebra of preemptive processes for verifying real-time systems with shared resources

AbstractThis paper describes a timed process algebra called TPAP. The aim of this algebra is to allow the modelisation of real time embedded processes sharing common resources, and which are sensitive to communication delays and scheduling strategies. Timed broadcasting and process preemption by interruption events are the two main fundamental notions of the algebra. They allow description of schedulers and asynchronous communication mediums, thus which can be taken into account when verifying the real time behaviour of the global system. We first present the process algebra and discuss its properties. A case study from the avionics area is then developed using TPAP, and formally verified by translation into the UPPAAL model checker

Process algebra for performance evaluation

This paper surveys the theoretical developments in the field of stochastic process algebras, process algebras where action occurrences may be subject to a delay that is determined by a random variable. A huge class of resource-sharing systems – like large-scale computers, client–server architectures, networks – can accurately be described using such stochastic specification formalisms. The main emphasis of this paper is the treatment of operational semantics, notions of equivalence, and (sound and complete) axiomatisations of these equivalences for different types of Markovian process algebras, where delays are governed by exponential distributions. Starting from a simple actionless algebra for describing time-homogeneous continuous-time Markov chains, we consider the integration of actions and random delays both as a single entity (like in known Markovian process algebras like TIPP, PEPA and EMPA) and as separate entities (like in the timed process algebras timed CSP and TCCS). In total we consider four related calculi and investigate their relationship to existing Markovian process algebras. We also briefly indicate how one can profit from the separation of time and actions when incorporating more general, non-Markovian distributions