A BSP Algorithm for the State Space Construction of Security Protocols

International audienceThis paper presents a Bulk-Synchronous Parallel (BSP) algorithm to compute the discrete state space of structured models of security protocols. The BSP model of parallelism avoids concurrency related problems (mainly deadlocks and non-determinism) and allows us to design an efficient algorithm that is at the same time simple to express. A prototype implementation has been developed, allowing to run benchmarks showing the benefits of our algorithm

A BSP algorithm for on-the-fly checking CTL* formulas on security protocols

International audienceThis paper presents a distributed (Bulk-Synchronous Parallel or bsp) algorithm to compute on-the-fly whether a structured model of a security protocol satisfies a ctl {Mathematical expression} formula. Using the structured nature of the security protocols allows us to design a simple method to distribute the state space under consideration in a need-driven fashion. Based on this distribution of the states, the algorithm for logical checking of a ltl formula can be simplified and optimised allowing, with few tricky modifications, the design of an efficient algorithm for ctl {Mathematical expression} checking. Some prototype implementations have been developed, allowing to run benchmarks to investigate the parallel behaviour of our algorithms

Interests groups in Parliament: Exploring MPs' interest affiliations (2000-2011)

This research note presents an innovative dataset of Swiss MPs' interest ties between 2000-2011. The longitudinal analysis shows that the average number of interest ties per MP has more than doubled: from 3.5 in 2000 to 7.6 in 2011. Since the mid-2000s, public interest groups have accounted for approximately one out of two ties between MPs and interest groups, showing the strongest increase during the period. However, when looking at the most present individual groups, important business groups dominate and appear well connected with the governmental parties of the political right. Finally, interest groups are also able to forge themselves a strategic presence within the parliamentary committees that are the most relevant for their policy issues. Next research steps include the assessment of the (un)biased access of interest groups to the parliamentary venue and their policy influenc

Approches fonctionnelles de la programmation parallèle et des méta-ordinateurs. Sémantiques, implantations et certification.

Some problems require performances that can only be provided by massively parallel machinesand meta-computers. Nevertheless, algorithm writing for this kind of machine remains more difficultthan for those strictly sequential and the conception of adapted languages is an active subject of researchnotwithstanding the frequent use of the concurrent programming. Indeed, the conception of a programminglanguage is the result of a compromise which determines balance between various qualities of the languagesuch as expressivity, safety, effectiveness or the simplicity of the semantics.In the prior works to this thesis, it was undertaken to study, with greater details, the intermediate positionthat the paradigm of the skeletons occupies. However, this did not involve conceiving an a priori fixed setsof operations and then to design performance models, but, to fix a structured parallelism model (with itsperformancemodel) and then to design a universal number of operations making it possible to program anyalgorithm of this model. The objective is therefore as follows : have an universal language in which theprogrammer can have an idea of the cost from the source code.This thesis comes under the project "CoordinAtion and Distribution of Multiprocessor Applications inobjective camL" (CARAML) of the ACI GRID. The objective was the development of libraries for highperformanceand globalised computations around the OCaml language. This project was organized in threesuccessive phases : safety and irregular data-parallel operations (mono-user) ; data-parallel multiprocessingoperations ; globalised operations for grid computing.The thesis follows the organization in three phases of the CARAML project and presents the contributionsof the author in each phase in the three parts : a semantic study of a functional language for BSP programmingand the certification of the written programs in this language ; a presentation of a primitive of parallelcomposition (and which also allows programming parallel "divide-and-conquer" algorithms), an exampleof application using an implementation of parallel data structures and an extension for parallel input/outputsin BSML ; the adaption of the language for meta-computing.Certains problèmes nécessitent des performances que seules les machines massivement parallèlesou les méta-ordinateurs peuvent offrir. L'écriture d'algorithmes pour ce type de machines demeureplus difficile que pour celles strictement séquentielles et la conception de langages adaptés est un sujet derecherche actif nonobstant la fréquente utilisation de la programmation concurrente. En effet, la conceptiond'un langage de programmation est le résultat d'un compromis qui détermine l'équilibre entre les différentesqualités du langage telles que l'expressivité, la sûreté, la prédiction des performances, l'efficacité oubien la simplicité de la sémantique.Dans des travaux antérieurs à cette thèse, il a été entrepris d'approfondir la position intermédiaire que leparadigme des patrons occupe. Toutefois il ne s'agissait pas de concevoir un ensemble a priori fixé d'opérationspuis de concevoir des méthodologies pour la prédiction des performances, mais de fixer un modèlede parallélisme structuré (avec son modèle de coûts) puis de concevoir un ensemble universel d'opérationspermettant de programmer n'importe quel algorithme de ce modèle. L'objectif est donc le suivant : parvenirà la conception de langages universels dans lesquels le programmeur peut se faire une idée du coût à partirdu code source.Cette thèse s'inscrit dans le cadre du projet «CoordinAtion et Répartition des Applications Multiprocesseursen objective camL» (CARAML) de l'ACI GRID dont l'objectif était le développement de bibliothèquespour le calcul haute-performance et globalisé autour du langage OCaml. Ce projet était organisé en troisphases successives : sûreté et opérations data-parallèles irrégulières mono-utilisateur ; opérations de multitraitementdata-parallèle ; opérations globalisées pour la programmation de grilles de calcul.Ce tapuscrit est organisé en 3 parties correspondant chacune aux contributions de l'auteur dans chacunedes phases du projet CARAML : une étude sémantique d'un langage fonctionnel pour la programmationBSPet la certification des programmes écrits dans ce langage ; une présentation d'une primitive de compositionparallèle (et qui permet aussi la programmation d'algorithmes «diviser-pour-régner» parallèles), un exempled'application via l'utilisation et l'implantation de structures de données parallèles et une extension pour lesentrées/sorties parallèles en BSML ; l'adaption du langage pour le méta-calcul