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Jeudi 6 Novembre
Heure: 16:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Introduction to Partial Order Reductions
Description: César Rodríguez In model checking, a well known source of state-space explosion (SSE) is the
explicit representation of concurrent actions by their interleavings.
Partial-order reductions (PORs) are a family of techniques attempting to
cope with this by constructing an equivalent state space where irrelevant
executions of the original are discarded.

This talk will be a gentle introduction to the topic. We will focus on
Godefroid's persistent sets, prove that a selective exploration based on
them visits all deadlocks, discuss the two main classes of algorithms for
computing them, and finish, time permitting, with an overview of the
conceptual similarities and differences between PORs and the unfolding
Mardi 18 Novembre
Heure: 14:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Cryptophie : Black-box Trace and Revoke Codes
Description: Phan Duong Hiuu
Jeudi 20 Novembre
Heure: 15:30 - 16:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Abstraction and Modular Verification of Services Using Symbolic Observation Graph (SOG)
Description: Hanene Ochi For automatically composing services in a correct manner, information about their behaviors (an abstract model) has to be published in a repository. This abstract model must be sufficient to decide whether two, or more, services are compatible (the composition is possible) without including any additional information that can be used to disclose the privacy of these services. The compatibility between two services can be based either on some generic properties or specific ones . This talk will present my work during my thesis about the problem considering these kinds of compatibility criteria, and we will introduce approches for the automatic abstraction of services and to the modular checking of their compatibility using their abstract models only. To abstract services, we use the symbolic observation graph (SOG) approach that preserves necessary informa tion for service composition and hides private information. We will show how the SOG can be adapted and used so that the verification of generic and specific compatibility criteria can be performed on the composition of the abstract models of services instead of the original composite service.
Vendredi 21 Novembre
Heure: 10:30 - 12:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Chemins en ludique non-linéaire
Description: Alice Pavaux La ludique est une théorie logique basée sur l'interaction, introduite il y a une quinzaine d'années par J.-Y. Girard. Elle s'inscrit dans un contexte marqué par les avancées importantes en théorie de la démonstration et en sémantique des langages de programmation permises par la logique linéaire. On se propose ici d'étudier les mécanismes de l'interaction dans une variante non-linéaire de la ludique, afin de poser les outils nécessaires à l'étude des types dans ce cadre. Cela se fera en décrivant les chemins suivis au cours de l'interaction au sein des desseins, les objets de la ludique. La non-linéarité permet de ne pas se restreindre au fragment multiplicatif-additif de la logique linéaire.
Mardi 25 Novembre
Heure: 14:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Le diamètre asymptotique des associaèdres généralisés
Description: Lionel Pournin Les associaèdres généralisés ont été introduits par SergeyFomin et Andrei Zelevinsky dans le cadre de la théorie des algèbresamassées, et réalisés géométriquement par Chapoton, Fomin etZelevinsky. Ils sont associés à n'importe quel groupe de Coxeter fini.Parmi eux figurent trois familles infinies de polytopes : lesassociaèdres de type A (associaèdres usuels), de type B ou C(cycloèdres), et de type D.Le diamètre asymptotique des associaèdres de types A, B (ou C), et Dest maintenant connu et cet exposé passera en revue les cas des typesB (ou C), et D. Les preuves ne seront pas données entièrement, maisseulement esquissées. Quelques questions associées seront finalementdiscutées.
Jeudi 27 Novembre
Heure: 16:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Precise Robustness Analysis of Real-Time Systems
Description: Étienne André Quantifying the robustness of a real-time system consists in
measuring the maximum extension of the timing delays such that the
system still satisfies its specification.
In this work, we introduce a more precise notion of robustness,
measuring the allowed variability of the timing delays in their
We consider here the formalism of time Petri nets extended with
inhibitor arcs.
We use the inverse method, initially defined for timed automata.
Its output, in the form of a parametric linear constraint relating
all timing delays, allows the designer to characterise the system local
robustness, and hence to identify the delays allowing the least variability.
We also exhibit a condition and a construction for rendering robust
a non-robust system.
This work is a joint work with Laure Petrucci.
Vendredi 28 Novembre
Heure: 11:00 - 12:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: New applications of moment-SOS hierarchies
Description: Victor Magron Semidefinite programming is relevant to a wide range of mathematic fields, including combinatorial optimization, control theory, matrix completion. In 2001, Lasserre introduced a hierarchy of semidefinite relaxations for particular polynomial instances of the Generalized Moment Problem (GMP). My talk emphasizes new applications of this moment-SOS hierarchy, investigated during my PhD and Postdoc research.

In the context of formal proofs for nonlinear optimization, one can combine the moment-SOS hierarchy with maxplus approximation of semiconvex functions. Such a framework is mandatory for formal certification of nonlinear inequalities, occurring by thousands in the proof of Kepler Conjecture by Hales.

I also present how to approximate, as closely as desired, the Pareto curve associated with bicriteria polynomial optimization problems or the projections of semialgebraic sets. For each problem, one builds a hierarchy of semidefinite programs, so that the sequence of bounds converges in L1 norm.

Finally, this hierarchy allows to analyze programs containing loop invariants with polynomial assignments.
Mardi 2 Décembre
Heure: 12:30 - 13:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Robust network design with uncertain outsourcing cost
Description: Michael Poss The expansion of a telecommunications network faces two sources of
uncertainty, which are the demand for traffic that shall transit through
the expanded network and the outsourcing cost that the network operator
will have to pay to handle the traffic that exceeds the capacity of its
network. The latter is determined by the future cost of
telecommunications services, whose negative correlation with the total
demand is empirically measured in the literature through the price
elasticity of demand. Unlike previous robust optimization works on the
subject, we consider in this paper both sources of uncertainty and the
correlation between them. The resulting mathematical model is a linear
program that exhibits a constraint with quadratic dependency on the
uncertainties. To solve the model, we propose a decomposition approach
that avoids considering the constraint for all scenarios. Instead, we
use a cutting plane algorithm that generates required scenarios on the
fly by solving linear multiplicative programs. Computational experiments
realized on the networks from SNDlib show that our approach is orders of
magnitude faster than the classical semidefinite programming
reformulation for such problems.
Heure: 14:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Analyse en moyenne d'algorithmes sur les graphes
Description: Vlady Ravelomanana
Mardi 9 Décembre
Heure: 12:30 - 13:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Complexity aspects of graph convexities
Description: Mitre Dourado In the first half of the talk, I will survey the basic concepts, problems and main known results related to computational complexity aspects of graph convexities. In the second half, I will present some new results on the Radon number in the geodetic convexity, among them a polynomial time algorithm for finding the Radon number of unit interval graphs.

This is a joint work with:
Jayme Luiz Szwarcfiter
Alexandre Toman
Heure: 14:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Asymptotic expansion for random tensor models
Description: Adrian Tanasa Three-dimensional random tensor models are a natural generalization ofthe celebrated matrix models. The associated tensor graphs, or 3Dmaps, can be classified with respect to a particular integer orhalf-integer, the degree of the respective graph.I will present in this talk a combinatorial analysis of the generalterm of the asymptotic expansion in N, the size of the tensor, of aparticular random tensor model, the so-called multi-orientable model.I will then present some enumerative results and show which are thedominant configurations of a given degree; several examples will alsobe given.
Jeudi 11 Décembre
Heure: 16:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: CosyVerif: An Open Source Extensible Verification Environment
Description: Étienne André Over the past two decades, numerous verification tools have been successfully used for verifying complex concurrent systems, modelled using various formalisms. However, it is still hard to coordinate these tools since they rely on such a large number of formalisms. Having a proper syntactical mechanism to interrelate them through variability would increase the capability of eff ective integrated formal methods. Here, we propose a modular approach for defining new formalisms by reusing existing ones and adding new features and/or constraints. Our approach relies on standard XML technologies; their use provides the capability of rapidly and automatically obtaining tools for representing and validating models. It thus enables fast iterations in developing and testing complex formalisms. As a case study, we applied our modular definition approach on families of Petri nets and timed automata. This work is implemented in the CosyVerif platform, a modular framework integrating verification software tools of the Paris regions.
This is a joint work with the CosyVerif team.
Vendredi 12 Décembre
Heure: 11:00 - 12:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Asynchronous Interaction with Theorem Provers: ProofGeneral's Last March
Description: Carst Tankink This year ProofGeneral, the generic Emacs-interface for proof assistants, celebrates its 20th birthday. The tool is showing its age, however, by only allowing a user to work at a single point at the time, and having to re-evaluate an entire proof script in reaction to changes at the beginning. In this talk, I will discuss our recent efforts to changing this situation: based on a previous endeavour in Isabelle, we have adapted the Coq proof assistant to work with the jEdit text editor. This editor has no user-visible notion of "State": the entire proof is always available to the proof assistant, allowing it to react to changes in the document in a more intelligent manner: by scheduling proofs in parallel and by postponing computation that are of no direct interest to the author. I will not go into full technical details in this talk, but give a demo of the current prototype, and discuss the ramifications of such a model in the longer term.
Mardi 16 Décembre
Heure: 14:10 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Plus long cycle dans les graphes aléatoires
Description: Vlady Ravelomanana
Heure: 15:10 - 18:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Dependence and phase change in random m-ary search trees
Description: Hsien-Kuei Hwang
Jeudi 18 Décembre
Heure: 16:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Teaching Formal Methods: Experience at UPMC and UP13 with CosyVerif
Description: Laure Petrucci Nowadays, students are more and more demanding for practical coursework,
which is a challenge when teaching formal approaches to software
engineering. The solution is to provide environments for such hands-on
sessions and homework, but this raises numerous difficulties. The
environment must be: (i) multi-platform (Mac OS, Linux, Windows) so as to
enable student practice at home, (ii) easy to deploy, (iii) easy to use and
to take charge of, and (iv) flexible enough to enable the integration of
new notations and associated services.

CosyVerif is a software environment dedicated to graphical notations, that
provides the mechanisms and means for an easy integration of additional
existing software for teaching (or demonstration) purposes. This makes it
an interesting platform to establish new courses.

This paper presents our experience using CosyVerif for teaching Petri nets
and parametric timed automata in two universities of the Paris region, i.e.
Université Pierre et Marie Curie, and Université Paris 13. We also use
CosyVerif to build demonstrators of Ph.D. students' work.