On convergence-sensitive bisimulation and the embedding of CCS in timed CCS

We propose a notion of convergence-sensitive bisimulation that is built just over the notions of (internal) reduction and of (static) context. In the framework of timed CCS, we characterise this notion of `contextual' bisimulation via the usual labelled transition system. We also remark that it provides a suitable semantic framework for a fully abstract embedding of untimed processes into timed ones. Finally, we show that the notion can be refined to include sensitivity to divergence

Introduction à l'analyse syntaxique et à la compilation

Engineering schoolCes notes de cours sont une introduction aux différentes phases de la compilation des langages de programmation. Après un survol de ces phases basé sur un petit langage d'expressions arithmétiques, on présente la théorie des grammaires algébriques LL et LR.On s'intéresse ensuite à l'évaluation et au typage en s'appuyant sur les techniques de la sémantique opérationnelle. On décline ces techniques dans le cadre de simples langages qui reflètent les styles de programmation impératif, à objets et fonctionnel. Enfin, on aborde les questions de la conception d'une machine virtuelle, de la gestion de la mémoire et de la traduction du langage source dans le langage d'une machine virtuelle

The SL synchronous language, revisited

International audienceWe revisit the SL synchronous programming model introduced by Boussinot and De Simone (IEEE, Trans. on Soft. Eng., 1996). We discuss an alternative design of the model including thread spawning and recursive definitions and we explore some basic properties of the revised model: determinism, reactivity, CPS translation to a tail recursive form, computational expressivity, and a compositional notion of program equivalence

Certifying cost annotations in compilers

We discuss the problem of building a compiler which can lift in a provably correct way pieces of information on the execution cost of the object code to cost annotations on the source code. To this end, we need a clear and flexible picture of: (i) the meaning of cost annotations, (ii) the method to prove them sound and precise, and (iii) the way such proofs can be composed. We propose a so-called labelling approach to these three questions. As a first step, we examine its application to a toy compiler. This formal study suggests that the labelling approach has good compositionality and scalability properties. In order to provide further evidence for this claim, we report our successful experience in implementing and testing the labelling approach on top of a prototype compiler written in OCAML for (a large fragment of) the C language

Appetite for destruction. Current interpretations of accidental or deliberate destructions in Bronze Age Cyprus

Destruction processes are considered 'time capsules of material culture' (Driessen 2013) as they freeze a site at one moment of its history providing key evidence for interpreting the archaeological record and reconstructing social, political, cultural and ideological circumstances. By focusing on selected case-studies, this paper aims at briefly discussing existing evidence of destruction events in Bronze Age contexts in Cyprus, and at a preliminary presentation of new research data resulting from ongoing interdisciplinary analyses at Middle Bronze Age Erimi

On the Decidability of Fragments of the Asynchronous Pi-Calculus

We study the decidability of a reachability problem for various fragments of the asynchronous $\pi$-calculus. We consider the combination of three main features: name generation, name mobility, and unbounded control. We show that the combination of name generation with either name mobility or unbounded control leads to an undecidable fragment. On the other hand, we prove that name generation without name mobility and with bounded control is decidable by reduction to the coverability problem for Petri Nets

Determinacy in a synchronous pi-calculus

To appear in the book `From semantics to computer science: essays in honor of Gilles Kahn', Cambridge University Press.The S-pi-calculus is a synchronous pi-calculus which is based on the SL model. The latter is a relaxation of the Esterel model where the reaction to the absence of a signal within an instant can only happen at the next instant. In the present work, we present and characterise a compositional semantics of the S-pi-calculus based on suitable notions of labelled transition system and bisimulation. Based on this semantic framework, we explore the notion of determinacy and the related one of (local) confluence

On the Reachability Problem in Cryptographic Protocols

We study the verification of secrecy and authenticity properties for cryptogra- phic protocols which rely on symmetric shared keys. The verification can be reduced to check whether a certain parallel program which models the protocol and the specification can reach an erroneous state while interacting with the environment. Assuming finite principals, we present a simple decision procedure for the reachability problem which is based on a symbolic' reduction system

An Elementary affine λ-calculus with multithreading and side effects (extended version)

Linear logic provides a framework to control the complexity of higher-order functional programs. We present an extension of this framework to programs with multithreading and side effects focusing on the case of elementary time. Our main contributions are as follows. First, we provide a new combinatorial proof of termination in elementary time for the functional case. Second, we develop an extension of the approach to a call-by-value $lambda$-calculus with multithreading and side effects. Third, we introduce an elementary affine type system that guarantees the standard subject reduction and progress properties. Finally, we illustrate the programming of iterative functions with side effects in the presented formalism

On the decidability of fragments of the asynchronous π-calculus

AbstractWe study the decidability of a reachability problem for various fragments of the asynchronous π-calculus. We consider the combination of three main features: name generation, name mobility, and unbounded control. We show that the combination of name generation with either name mobility or unbounded control leads to an undecidable fragment. On the other hand, we prove that name generation without name mobility and with bounded control is decidable by reduction to the coverability problem for Petri Nets