Abstract. The ambient calculus was designed to model mobile processes and study their properties. A first type system was proposed by Cardelli-Gordon-Ghelli to prevent run-time faults. We extend it by introducing subtyping and present a type-checking algorithm which returns a minimal type relatively to this system. By the way, we also add two new constructs to the language. Finally, we remove the type annotations from the syntax and give a type-inference algorithm for the original type system.

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Cooperation of cars capable to communicate bears a high potential with respect to safety in critical situations. Following a top-down design, cars form cooperative groups, exchange information available to them and establish a common relevant picture upon which critical situations are detected, optimal decisions for the groups are derived and are distributed in form of individual action sequences. This paper focuses on the formation of cooperative groups. To this end, a graph-based spatiotemporal distance measure is developed, using the concept of virtual meeting points within the road infrastructure. The distance measure is analyzed and it serves to define cooperative groups of cognitive automobiles.

In order to answer the challenge of pervasive computing, we propose a new process calculus, whose aim is to describe dynamic systems composed of agents able to move and react differently depending on their location. This Context-Aware Calculus features a hierarchical structure similar to mobile ambients, and a generic multi-agent synchronization mechanism, inspired from the join-calculus. After general ideas and introduction, we review the full calculus' syntax and semantics, as well as some motivating examples, study its expressiveness, and show how the notion of computation itself can be made context-dependent.

We consider the Pure Safe Ambient Calculus, which is Levi and Sangiorgi's Safe Ambient Calculus (a variant of Cardelli and Gordon's Mobile Ambient Calculus) restricted to its mobility primitives-in particular, we focus on its expressive power. Since it has no form of communication or substitution, we show how these notions can be simulated by mobility and modifications in the hierarchical structure of ambients. As a main result, we use these techniques to design an encoding of the synchronous π-calculus into pure ambients, and we study its correctness, thus showing that pure ambients are as expressive as the π-calculus. In order to simplify the proof and give an intuitive understanding of the encoding, we design an intermediate language, the π-Calculus with Explicit Substitutions and Channels, which is an extension of the π-calculus in which communication and substitution are broken into simpler steps, and we show that is has the same expressive power as the π-calculus.