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Mercredi 31 mars 2021, 11h - 12h, Https://meet.jit.si/SeminaireLRDE \& Amphi 4

Contributions to Boolean satisfiability solving and its application to the analysis of discrete systems

Souheib Baarir, Université Paris VI

Despite its NP-completeness, propositional Boolean satisfiability (SAT) covers a broad spectrum of applications. Nowadays, it is an active research area finding its applications in many contexts like planning decision, cryptology, computational biology, hardware and software analysis. Hence, the development of approaches allowing to handle increasingly challenging SAT problems has become a major focus: during the past eight years, SAT solving has been the main subject of my research work. This talk presents some of the main results we obtained in the field.

Souheib Baarir est Docteur en informatique de l'Université de Paris VI depuis 2007 et a obtenu son HDR à Sorbonne Université en 2019. Le thème de ses recherches s'inscrit dans le cadre des méthodes formelles de vérification des systèmes concurrents. En particulier, il s’intéresse aux méthodes permettant d’optimiser la vérification en exploitant le parallélisme et/ou les propriétés de symétries apparaissant dans de tels systèmes.

https://www.lip6.fr/actualite/personnes-fiche.php?ident=P617

Mercredi 10 février 2021, 11h - 12h, Https://meet.jit.si/SeminaireLRDE

Generating Posets Beyond N

Uli Fahrenberg, Ecole Polytechnique

We introduce iposets - posets with interfaces - equipped with a novel gluing composition along interfaces and the standard parallel composition. We study their basic algebraic properties as well as the hierarchy of gluing-parallel posets generated from singletons by finitary applications of the two compositions. We show that not only series-parallel posets, but also interval orders, which seem more interesting for modeling concurrent and distributed systems, can be generated, but not all posets. Generating posets is also important for constructing free algebras for concurrent semi-rings and Kleene algebras that allow compositional reasoning about such systems.

Ulrich (Uli) Fahrenberg holds a PhD in mathematics from Aalborg University, Denmark. He has started his career in computer science as an assistant professor at Aalborg University. Afterwards he has worked as a postdoc at Inria Rennes, France, and since 2016 he is a researcher at the computer science lab at École polytechnique in Palaiseau, France. Uli Fahrenberg works in algebraic topology, concurrency theory, real-time verification, and general quantitative verification. He has published more than 80 papers in computer science and mathematics. He has been a member of numerous program committees, and since 2016 he is a reviewer for AMS Mathematical Reviews.

http://www.lix.polytechnique.fr/~uli/bio.html

Mercredi 16 décembre 2020, 11h - 12h, {\small https://eu.bbcollab.com/collab/ui/session/guest/95a72a9dc7b0405c8c281ea3157e9637}

Diagnosis and Opacity in Partially Observable Systems

Stefan Schwoon, ENS Paris-Saclay

In a partially observable system, diagnosis is the task of detecting certain events, for instance fault occurrences. In the presence of hostile observers, on the other hand, one is interested in rendering a system opaque, i.e. making it impossible to detect certain "secret" events. The talk will present some decidability and complexity results for these two problems when the system is represented as a finite automaton or a Petri net. We then also consider the problem of active diagnosis, where the observer has some control over the system. In this context, we study problems such as the computational complexity of the synthesis problem, the memory required for the controller, and the delay between a fault occurrence and its detection by the diagnoser. The talk is based on joint work with B. Bérard, S. Haar, S. Haddad, T. Melliti, and S. Schmitz.

Stefan Schwoon studied Computer Science at the University of Hildesheim and received a PhD from the Technical University of Munich in 2002. He held the position of Scientific Assistent at the University of Stuttgart from 2002 to 2007, and at the Technical University in Munich from 2007 to 2009. He is currently Associate Professor (Maître de conférences) at Laboratoire Spécification et Vérification (LSV), ENS Paris-Saclay, and a member of the INRIA team Mexico. His research interests include model checking and diagnosis on concurrent and partially-observable systems.

http://www.lsv.fr/~schwoon/

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