Xavier Nicollin

Learn More
We present a general framework for the formal specification and algorithmic analysis of hybrid systems. A hybrid system consists of a discrete program with an analog environment. We model hybrid systems as finite automata equipped with variables that evolve continuously with time according to dynamical laws. For verification purposes, we restrict ourselves(More)
We describe nite-state programs over real-numbered time in a guardedcommand language with real-valued clocks or, equivalently, as nite automata with real-valued clocks. Model checking answers the question which states of a real-time program satisfy a branching-time speci cation (given in an extension of CTL with clock variables). We develop an algorithm(More)
We study a process algebra ATP for the description and analysis of systems of timed processes. An important feature of the algebra is that its vocabulary of actions contains a distinguished element . An occurrence of is a time event representing progress of time. The algebra has, apart from standard operators of process algebras like CCS or ACP, a primitive(More)
We propose a method for the implementation and analysis of real-time systems, based on the compilation of speci cations into extended automata. Such a method has been already adopted for the so called \synchronous" real-time programming languages. The method is illustrated for a simple speci cation language that can be viewed as the extension of a language(More)
The paper presents results of ongoing work aiming at the unification of some behavioral description formalisms for timed systems. We propose for the algebra of timed processes ATP a very general semantics in terms of a time domain. It is then shown how ATP can be translated into a variant of timed graphs. This result allows the application of existing(More)
This paper addresses the problem of automatizing the production of test sequences for reactive systems. We particularly focus on two points: (1) generating relevant inputs, with respect to some knowledge about the environment in which the system is intended to run; (2) checking the correctness of the test results, according to the expected behavior of the(More)
Architecture description languages are used to describe both the hardware and software architecture of an application, at system-level. The basic software components are intended to be developed independently, and then deployed on the described architecture. This separate development of the architecture and of the software raises the problem of early(More)
Many embedded reactive programs perform computations at different rates, while still requiring the overall application to satisfy very tight temporal constraints. We propose a method to automatically distribute programs such that the obtained parts can be run at different rates, which we call <i>rate desynchronization</i>. We consider general programs whose(More)