Abstract. We address the verification of communication protocols or distributed systems that can be modeled by Communicating Finite State Machines (CFSMs), i.e. a set of sequential machines communicating via unbounded FIFO channels. Unlike recent related works based on acceleration techniques, we propose to apply the Abstract Interpretation approach to such systems, which consists in using approximated representations of sets of configurations. We show that the use of regular languages together with an extrapolation operator provides a simple and elegant method for the analysis of CFSMs, which is moreover often as accurate as acceleration techniques, and in some cases more expressive. Last, when the system has several queues, our method can be implemented either as an attribute-independent analysis or as a more precise (but also more costly) attribute-dependent analysis.

Abstract-In this paper, we investigate the control of infinite systems, modeled by symbolic transition system for safety properties. We first redefine the concept of controllability by applying it to the guards of symbolic transitions, instead of to the events. We then define synthesis algorithms based on symbolic transformations and abstract interpretation techniques so that we can ensure finiteness of the computations.

Abstract. This paper proposes a new abstract domain for languages on infinite alphabets, which acts as a functor taking an abstract domain for a concrete alphabet and lift it to an abstract domain for words on this alphabet. The abstract representation is based on lattice automata, which are finite automata labeled by elements of an atomic lattice. We define a normal form, standard language operations and a widening operator for these automata. We apply this abstract lattice for the verification of symbolic communicating machines, and we discuss its usefulness for interprocedural analysis.

Abstract-We consider the control of distributed systems composed of subsystems communicating asynchronously; the aim is to build local controllers that restrict the behavior of a distributed system in order to satisfy a global state avoidance property. We model our distributed systems as communicating finite state machines with reliable unbounded FIFO queues between subsystems. Local controllers can only observe their proper local subsystems and do not observe the queues. To refine their control policy, they can use the FIFO queues to communicate by piggybacking extra information to the messages sent by the subsystems. We define synthesis algorithms allowing to compute the local controllers. We explain how we can ensure the termination of this control algorithm by using abstract interpretation techniques, to overapproximate queue contents by regular languages. An implementation of our algorithms provides an empirical evaluation of our method. I. INTRODUCTIONIn the framework of control of distributed systems, two classes of systems are generally considered, depending on whether the communications between subsystems are synchronous or not. When the synchrony hypothesis [3] can be made, the decentralized control problem and the modular control problem address the design of coordinated controllers that jointly ensure the desired properties for this kind of systems [26], [22], [21], [9], [13]. When considering asynchronous distributed systems, one have to take into account some communication delays between the components of the system, which renders the distributed control problem much harder even undecidable [24].We are here interested in the second problem i.e., the distributed control problem. Our aim is to solve this problem when the system to be controlled is composed of n subsystems that asynchronously communicate through reliable unbounded FIFO channels (or queues). These subsystems are modeled by communicating finite state machines [5] (CFSM for short) that explicitly express the work and communications of a distributed system. This model appears to be essential for concurrent systems in which components cooperate via asynchronous message passing through unbounded buffers (they are e.g. widely used to model communication protocols). We thus assume that the distributed system is already built and the architecture of communication between the different subsystems is fixed. Following the architecture described in Figure 1, we assume that each subsystem is