Laboratoire d'informatique de l'École polytechnique


Local limit of random discrete surface with (or without !) a statistical physics model.

Speaker: Marie Albenque (Combi team)
Location: Amphi Sophie Germain (+
Date: Thu, 16 Dec 2021, 13:00-14:00

Random planar maps (which correspond to planar graphs embedded in the plane) are a very natural model of random discrete surface, which have been widely studied in these last 30 years (in particular by several members of the Combi team !). In my talk, I will present some results of convergence — in the local limit sense, as introduced by Benjamini and Schramm – for those models. I will try to give an overview of this field: I will first consider models of maps which are sampled from a uniform distribution, for which many results are available. I will then move to random planar maps sampled with a weight which comes from a statistical physics model, for which many problems are still open and yield fascinating research perspectives.

Talk by Rim Rammal: « Differential flatness for fractional order dynamic systems »

Speaker: Rim Rammal (Université Toulouse III - Paul Sabatier)
Location: Room Henri Poincaré
Date: Tue, 14 Dec 2021, 11:00-12:00

Abstract: Differential flatness is a property of dynamic systems that allows the expression of all the variables of the system by a set of differentially independent functions, called flat output, depending on the variables of the system and their derivatives. The differential flatness property has many applications in automatic control theory, such as trajectory planning and trajectory tracking. This property was first introduced for the class of integer order systems and then extended to the class of fractional order systems. This talk will present the flatness of the fractional order linear systems and more specifically the methods for computing fractional flat outputs.

Further details can be found on the webpage of the seminar:

Talk by Mohab Safey El Din: « msolve: a library for solving multivariate polynomial systems »

Speaker: Mohab Safey El Din (Sorbonne Université)
Location: Room Grace Hopper
Date: Tue, 7 Dec 2021, 11:00-12:00

Abstract: In this talk, we present a new open source library, developed with J. Berthomieu (Sorbonne Univ.) and C. Eder (TU Kaiserslautern) named msolve, for solving multivariate polynomial systems through computer algebra methods. Its core algorithmic framework relies on Gröbner bases and linear algebra based algorithms. This includes J.-C. Faugère’s F4 algorithm, recent variants of the FGLM change of ordering and real root isolation.This talk will cover a short presentation of the current functionalities provided by msolve, followed by an overview of the implemented algorithms which will motivate the design choices underlying the library. We will also compare the practical performances of msolve with leading computer algebra systems such as Magma, Maple, Singular, showing that msolve can tackle systems which were out of reach by the computer algebra software state-of-the-art. If time permits, we will report on new algorithmic developments for ideal theoretic operations (joint work with J. Berthomieu and C. Eder) and change of orderings algorithms (joint work with J. Berthomieu and V. Neiger).

Further details can be found on the webpage of the seminar:

Soutenance de thèse d'Isabella Panaccione : « Sur des algorithmes de décodage de codes géométriques au delà de la moitié de la distance minimale »

Speaker: Isabella Panaccione
Location: Amphi. Sophie Germain
Date: Ven. 3 déc. 2021, 09h30-11h30

Isabella Panaccione, doctorante dans l’équipe Grace, soutiendra sa thèse intitulée « Sur des algorithmes de décodage de codes géométriques au delà de la moitié de la distance minimale », le vendredi 3 Décembre à 9h30 à Inria Saclay, bâtiment Turing, salle Sophie Germain au niveau 0.

Algorithmic Law and Society

Location: HEC
Date: Wed, 1 Dec 2021, 08:00 - Fri, 3 Dec 2021, 18:00

DaSciM is co-organizing the workhop “Algorithmic Law and Society” which will take place to HEC from December 1st to the 3rd. Visit the website and feel free to register.

Talk by Torsten Mütze: « Combinatorial generation via permutation languages ».

Speaker: Torsten Mütze (University of Warwick)
Location: Zoom
Date: Lun. 29 nov. 2021, 15h00-16h00

La prochaine séance du séminaire de combinatoire du plateau de Saclay aura lieu ce lundi 29 novembre à 15h en ligne (informations de connexion ci-dessous) avec retransmission en salle Philippe Flajolet du LIX. Nous aurons le plaisir d’écouter Torsten Mütze (University of Warwick) nous parler de « Combinatorial generation via permutation languages ». Le résumé et les informations de connexion sont disponibles ci-dessous.

Résumé : In this talk we present a versatile algorithmic framework for exhaustively generating a large variety of different combinatorial objects, based on encoding them as permutations. This framework provides a unified view on many known Gray code results and allows us to prove many new ones, and it yields efficient algorithms for computing Hamilton paths and cycles on large classes of polytopes. We give an overview of the ingredients of the framework, and we present two of its main applications: (1) the generation of pattern-avoiding permutations (see; (2) the generation of lattice congruences of the weak order on the symmetric group. This talk is based on joint work with Liz Hartung, Hung P. Hoang, and Aaron Williams (SODA 2020).


Le programme du séminaire est disponible sur la page