Abstract. An impure language is one that combines functional and imperative constructs. We propose a method for ensuring termination of impure concurrent languages that makes it possible to combine term rewriting measure-based techniques with traditional approaches for termination in functional languages such as logical relations. The method can be made parametric on the termination technique employed on the functional part; it can also be iterated. We illustrate the method in the case of a π-calculus with both functional and imperative names, and show that, with respect to previous approaches to termination, it allows us to extend considerably the set of processes that can be handled. The method can also be applied to sequential languages, e.g., λ-calculi with references.

Abstract. We give an axiomatisation of strong bisimilarity on a small fragment of CCS that does not feature the sum operator. This axiomatisation is then used to derive congruence of strong bisimilarity in the finite π-calculus in absence of sum. To our knowledge, this is the only nontrivial subcalculus of the π-calculus that includes the full output prefix and for which strong bisimilarity is a congruence.

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Abstract. This paper surveys some recent works on the study of termination in a concurrent setting. Processes are π-calculus processes, on which type systems are imposed that ensure termination of the process computations. Two approaches are exposed. The rst one draws on the method of logical relations, which has been extensively used in the analysis of sequential languages. The second approach exploits notions from term rewriting.

Abstract. The Ambient Logic (AL) has been proposed for expressing properties of process mobility in the calculus of Mobile Ambients (MA), and as a basis for query languages on semistructured data.In this paper, we study the expressiveness of AL. We define formulas for capabilities and for communication in MA. We also derive some formulas that capture finitess of a term, name occurrences and persistence. We study extensions of the calculus involving more complex forms of communications, and we define characteristic formulas for the equivalence induced by the logic on a subcalculus of MA. This subcalculus is defined by imposing an image-finiteness condition on the reducts of a MA process.

Current software and hardware systems, being parallel and reconfigurable, raise new safety and reliability problems, and the resolution of these problems requires new methods. Numerous proposals aim at reducing the threat of bugs and preventing several kinds of attacks. In this paper, we develop an extension of the calculus of mobile ambients, named controlled ambients, that is suited for expressing such issues, specifically denial of service attacks. We present a type system for controlled ambients, which makes static resource control possible in our setting, and enhance it with a rich notion of resources.

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