Laboratoire de Mathématiques de Besançon - UMR 6623 CNRS
UFC
CNRS


Accueil > Agenda scientifique

Les événements de février 2021

Séminaire

  • Analyse Numérique et Calcul Scientifique

    • Jeudi 4 février 11:00-12:00 - Charles Dapogny - Laboratoire Jean Kuntzmann

      Séminaire d’Analyse Numérique et Calcul Scientifique

      Lieu : En ligne

      Article

    • Jeudi 11 février 11:00-12:00 - Havva Yoldaş - Institut Camille Jordan (ICJ)

      Séminaire d’Analyse Numérique et Calcul Scientifique

      Résumé : Analysis of a cross-diffusion model for rival gangs interaction in a city
      In this talk, I will present a two-species cross-diffusion model inspired by a system of convection-diffusion equations. The latter system is derived from an agent-based model on a two-dimensional discrete lattice and proposed to simulate gang territorial development through graffiti markings. We provide a weak stability analysis on the cross-diffusion system by using entropy balance inequalities. We show that the system does not allow segregated solutions.
      This is talk is based on a joint work with Alethea B. T. Barbaro (U. Delft), Nancy Rodriguez (U. Colorado Boulder) and Nicola Zamponi (U. Mannheim).

      Lieu : En ligne

      Article

  • Probabilités et statistique

    • Lundi 22 février 11:00-12:00 - Quentin Klopfenstein - IMB, Univ. Bourgogne Franche-Comté

      Séminaire PS : Implicit differentiation for fast hyperparameter selection in non-smooth convex learning

      Résumé : Most modern machine learning models require one hyperparameter to be chosen by the user upstream of the learning phase. Popular approaches use a grid of values on which to evaluate the performance of the model for a given criterion, one can think of grid-search or random-search which means fitting the given model for each value of the grid.
      These methods have a major drawback : they scale exponentially with the number of hyperparameters. In this presentation, we will show that the hyperparameter selection problem can be cast as a bilevel optimization problem and will consider non-smooth models (such as the Lasso, the Elastic Net, the SVM).
      We propose a first-order method that uses information about the gradient with respect to the hyperparameter to automatically select the best hyperparameter for a given criterion.
      We will see that this method is very efficient even when the number of hyperparameters gets large.

      Article

  • Analyse Fonctionnelle

    • Mardi 23 février 13:45-15:00 - Michael Brannan - Texas A&M University

      Séminaire d’Analyse Fonctionnelle

      Article

    • Mardi 23 février 16:00-17:00 - Michael Brannan - Texas A&M

      Complete logarithmic Sobolev inequalities and non-commutative Ricci curvature

      Résumé : I will give a brief introduction to the study of log-Sobolev type inequalities (LSI’s) for quantum Markov semigroups and some of their applications. In the context of classical heat semigroups on compact Riemannian manifolds, the famous Bakry-Emery theorem provides a beautiful connection between the geometry of the underlying manifold and the LSI, showing that a positive lower bound on the Ricci curvature implies an LSI for the heat semigroup. I will discuss an information-theoretic approach to obtain modified log-Sobolev inequalities based on non-positive non-commutative Ricci curvature lower bounds previously developed by Carlen and Maas. Using these tools, we are able to find new examples of quantum Markov semigroups satisfying a completely bounded version of the modified LSI, including heat semigroups on free quantum groups. This talk is based on joint work with Li Gao (TUM) and Marius Junge (UIUC).

      Article

Colloque / Journée

  • Fédération

    • Du 4 au 5 février -

      Ecole d’Hiver en Statistiques Besançon-Dijon

      Lieu : En visioconférence

      Article

Réunion

  • LMB

    • Vendredi 26 février 12:30-14:00 -

      Conseil de Laboratoire

      Lieu : En visioconférence

      Article

  • LMB

    • Lundi 1er février 12:30-14:00 -

      Commission Informatique (CI)

      Lieu : En visioconférence

      Article

  • Département de Mathématiques

    • Vendredi 12 février 12:30-14:00 -

      Réunion du LmB et du Département de mathématiques

      Lieu : En visioconférence

      Article

Soutenance

  • Doctorant

    • Mardi 9 février 14:00-16:00 -

      Soutenance de thèse d’Olivier ARRIGONI

      Lieu : UFR ST

      Article

Ajouter un événement