Graphes et Logique
Mercredi 30 avril 2025, 13 heures 30, Salle 1021
Sylvain Schmitz (IRIF) Well quasi-orders and preservation theorems for First-Order Logic - Part II
Théorie des Topos
Mercredi 30 avril 2025, 14 heures, Salle 3052
Umberto Tarantino Elementary topoi (chapter IV)
Preuves, programmes et systèmes
Vendredi 2 mai 2025, 10 heures 30, Salle 3052 & online (Zoom link)
Quantale-Valued Modal Logic (Chapman University) Alexander Kurz
Algorithmes et complexité
Lundi 5 mai 2025, 11 heures, Salle 3052
Ryu Hayakawa (Kyoto University) Quantum and classical complexities in the homology of higher-order networks
Programmation
Lundi 5 mai 2025, 10 heures, 3071
Timothy Bourke (INRIA) Une interface entre OCaml et la bibliothèque Sundials des solveurs numériques
Théorie des Topos
Mercredi 7 mai 2025, 14 heures, Salle 3052
Vincent Moreau Lawvere-Tierney topologies (chapter V)
Automates
Vendredi 9 mai 2025, 14 heures, Salle 3052
Quentin Aristote (IRIF) Learning automata weighted over number rings, concretely (and categorically)
We show that number rings are what we call “almost strong Fatou”: if an n-state automaton weighted in a number field recognizes an integer-valued series, then it admits an equivalent n+1-state automaton weighted in the corresponding ring of integers.
We give a polynomial-time algorithm for computing such an n+1-state automaton, and show that removing any more states is at least as hard as solving the principal ideal problem, for which the best currently known algorithm is in quantum polynomial time.
Finally, we will see how this procedure can be used to reduce active learning problems in number rings to active learning problems in fields. If time allows, I will also give a brief teaser of how this generalizes to a generic reduction procedure between active learning problems for automata valued in different categories. These categorical aspects will be further developed on May 15th for a talk at the AutCat seminar.
Vérification
Lundi 12 mai 2025, 11 heures, 3052 and Zoom link
Jeroen Keiren (Eindhoven University of Technology) An Expressive Timed Modal Mu-Calculus for Timed Automata
In this talk, I present a timed model mu-calculus $L_{rel}^{\mu,\nu}$ for encoding properties of systems modeled as timed automata. Our logic includes arbitrary fixpoints and an until-like modal operator for time elapses, and is shown to be strictly more expressive than existing timed modal mu-calculi introduced in the literature. It also enjoys decidable model checking, as it respects the traditional region-graph construction for timed automata. Additionally, I establish that, in contrast to other timed mu-calculi, $L_{rel}^{\mu,\nu}$ is strictly more expressive than Timed Computation Tree Logic (TCTL) in the setting of general timed automata, meaning that model checkers for $L_{rel}^{\mu,\nu}$ are immediately usable as model checkers for TCTL for general timed automata.
This is joint work with Rance Cleaveland and Peter Fontana, and appeared as [1].
[1] Cleaveland, R., Keiren, J.J.A., Fontana, P.: An Expressive Timed Modal Mu-Calculus for Timed Automata. In: Hillston, J. et al. (eds.) Quantitative Evaluation of Systems and Formal Modeling and Analysis of Timed Systems., pp. 160–178. Springer Nature Switzerland, Cham (2024).
One world numeration seminar
Mardi 13 mai 2025, 14 heures, Online
Artem Dudko (IM PAN) On attractors of Fibonacci maps
In the talk I will present an approach for studying attractors of maps, which are periodic points of a renormalization. Using this approach and rigorous computer estimates, we show that the Fibonacci map of degree $d=3.8$ does not have a wild attractor, but that for degree $d=5.1$ the wild attractor exists. The talk is based on a joint work with Denis Gaidashev.
Séminaire des membres non-permanents
Jeudi 15 mai 2025, 16 heures, Salle 3052
Lucas Pouillart Non encore annoncé.