Journées ANR Conviviality

20 mai 2026, 14:00 → 22 mai 2026, 14:00 Europe/Paris

Journées de Toulouse de l'ANR Conviviality (lien vers la page du projet)

Organisateurs locaux : Fanny Delebecque et Aldéric Joulin

mer. 20 mai

14:00 → 15:00 TBA

Orateur: Michel Bonnefont

15:00 → 16:00 On set-valued intertwining duality for diffusion processes

Markov intertwinning relations were first developed in the finite state space setting to provide a probabilistic approach to convergence to equilibrium.
We will see how to adapt this method to diffusions on Riemannian manifolds, through stochastic extensions of mean curvature flows.

Orateur: Laurent Miclo

16:00 → 16:30 Pause

16:30 → 17:30 TBA

Orateur: Marjolaine Puel

17:30 → 18:00 On weighted Poincaré inequalities for multivariate Liouville and elliptical distributions - Application to Global Sensitivity Analysis

In this work, we develop new weighted Poincaré inequalities for two clases of multivariate probability measures: multivariate Liouville and elliptical contoured distributions. The former are established via a radial-type decomposition involving the Dirichlet distribution, while the latter are obtained through their spherical counterparts. We further extend this type of results to measures with prescribed copulas. Finally, we apply these results to global sensitivity analysis and illustrate their practical use in a flood model case study.

Orateur: David Heredia

18:00 → 18:30 TBA

Orateur: Ons Rameh

jeu. 21 mai

09:00 → 09:30 Sub-exponential tails in biased run and tumble equations with unbounded velocities

Run and tumble equations are widely used models for bacterial chemotaxis. In this talk, we present the long-time behavior of run and tumble equations with unbounded velocities. We show existence, uniqueness and quantitative convergence towards a steady state. In contrast to the bounded velocity case, the equilibrium has sub-exponential tails and we have sub-exponential rate of convergence to equilibrium. This produces additional technical challenges. We are able to successfully adapt both Harris' type and L²-hypocoercivity. This is joint work with Emeric Bouin and Josephine Evans.

Orateur: Luca Ziviani

09:30 → 10:30 TBA

Orateur: Jordan Serres

10:30 → 11:00 Pause

11:00 → 11:30 Régularité des équations elliptiques à poids monomiaux

Dans cet exposé je présenterai des théorèmes de régularité $C^{0,\alpha}$ et $C^{1,\alpha}$ pour solutions d'équations elliptiques, en forme de divergence, avec poids monomiaux. A cause de la dégéneration/singularité des poids (qui ne sont pas forcement dans la classe des poids Muckenhoupt $A_2$) la théorie classique ne s'applique pas. Grace à des théorèmes d'approximations et à des inegalités de Sobolev uniformes en $\epsilon$ on pourra quand même démontrer la régularité holderienne des solutions. C'est un travail fait en collaboration avec G. Cora, G. Fioravanti et S. Vita.

Orateur: Francesco Pagliarin

11:30 → 12:00 TBA

Orateur: Tom Maitre

12:00 → 14:00 Repas

14:00 → 15:00 Les variables sous-gaussiennes sont somme de trois gaussiennes, d'après A. Song

Dans cet exposé, je présenterai des résultats récents de Antoine Song sur une conjecture prédisant que les variables 1 sous-gaussiennes peuvent être réalisées comme sommes d'un nombre borné de variables gaussiennes standard, en toutes dimensions. Song démontre cette conjecture en dimension 1, et donne des nouvelles estimations sur le nombre de gaussiennes nécessaires en dimension supérieure. Je parlerai aussi des motivations de ce problème, issues de la géométrie des convexes.

Orateur: Max Fathi

15:00 → 15:30 TBA

Orateur: Andreas Malliaris

15:30 → 16:00 Pause

16:00 → 17:00 TBA

Orateur: Pierre Gervais

17:00 → 17:30 Low-temperature asymptotics of the Poincaré and the log-Sobolev constants for Łojasiewicz potentials

In 2024, Chewi and Stromme showed that, in the low-temperature regime, the behavior of the relative entropy with respect to a Gibbs measure reflects that of the underlying potential when the latter has a unique minimizer. They conjectured that this link extends more generally to potentials having multiple minimizers.
In this talk, we show that this is not the case. We explain that when there are multiple minimizers, the geometry of the set of minimizers plays a direct role in how the constants in functional inequalities behave at low temperature.

Orateur: Aziz Ben Nejma

17:30 → 18:15 TBA

Orateur: Ivan Gentil

ven. 22 mai

09:00 → 10:00 TBA

Orateur: Patrick Cattiaux

10:00 → 10:45 TBA

Orateur: Louis-Pierre Chaintron

10:45 → 11:15 Pause

11:15 → 11:45 TBA

Orateur: Paul Invernizzi

11:45 → 12:30 Active Brownian particles with mean-field interaction: singular interactions and multiple invariant measures

We introduce a mean-field McKean-Vlasov model for a collective of ants. The model sustains two non-trivial dynamical behaviours: aggregation and lane formation. We show the well-posedness and mean-field limit for the particle model with singular interactions via a compactness method. We also show the existence of multiple invariant measures via perturbative Fourier-style bifurcation analysis, reflecting the aggregation and lane formation behaviours (joint work with Matthias Rakotomalala). We conclude with some open problems pertaining to interacting active Brownian particle models.

Orateur: Oscar de Wit

12:30 → 14:00 Repas