Conférence pour les 50 ans du CMAP

Contribution List

1. Ouverture et mot des tutelles : Amphi Faurre 13:20 - 13:40

9/11/24, 1:20 PM

Séance d'ouverture de la conférence

2. T. Bodineau : Statistical properties of a hard sphere gas

9/11/24, 1:40 PM

A gas dynamics can be modelled by a billiard made of hard spheres, moving according to the laws of classical mechanics. Initially the spheres are randomly distributed according to a probability measure which is then transported by the flow of the deterministic dynamics. Since the seminal work of Lanford, it is known that the gas density converges in the kinetic limit towards the Boltzmann...

3. N. Spillane : Convergence and acceleration of GMRES for solving linear systems

9/11/24, 2:20 PM

The GMRES linear solver, introduced by Y. Saad et M. H. Schultz is the go-to solver for non-symmetric systems that are too large to be factorized. For general matrices, the convergence behaviour of GMRES is not fully understood. Theoretical analysis is a challenge in itself but it also has very important practical implications.

In this talk I will present some existing convergence results...

4. S. Allassonnière : Intelligence artificielle en santé : actualités et perspectives.

9/11/24, 3:30 PM

Along my years in the CMAP, I have been able to work with my students on several projects that I will quickly describe here.

First we have provided coherent framework for studying cross-sectional, multimodal and longitudinal manifold-valued data. We have introduced Bayesian mixed-effect models which allow to estimate both a group-representative piecewise-geodesic trajectory in the...

5. S. Mallat : Des IA génératives jusqu'à la physique statistique

9/11/24, 4:10 PM

Les algorithmes de génération d'images par réseaux de neurones peuvent synthétiser des images de qualités spectaculaires. Es-ce une forme de mémorisation ou sont ils capable de généraliser ? Comment peuvent ils contourner la malédiction de la dimensionnalité, pour des images aussi complexes que celles de notre environnement ? Ces algorithmes échantillonnent des distributions de probabilités,...

6. Session Poster - Apéritif salé et sucré

9/11/24, 5:00 PM

7. C. Hillairet : Actuarial modeling for the systemic component of Cyber-risk

9/12/24, 9:30 AM

With the rise of digital economy, cyber risk has become a major threat for the financial system, while the scale of losses linked to cyber-risk is rising sharply (more than 1% of the global GDP). Facing this risk, cyber insurance is an essential lever for economic resilience, but its development encounters some pitfalls, with important uncertainties. Indeed the emerging and evolving nature...

8. J.-M. Roquejoffre : Large time dynamics in the Fisher-KPP equation

9/12/24, 10:10 AM

The Fisher-KPP equation (the acronym KPP stands for Kolmogorov, Petrovskii and Piskunov) is an ubiquitous model that arises in the applied sciences, such as ecology or combustion science. It aslo arises in probability theory, as its solution starting from an appropriate initial datum accounts for the behaviour of the rightmost particle in the one-dimensional Branching Brownian Motion.

In a...

9. D. Villemonais : Binary branching processes with Moran type interactions

9/12/24, 11:20 AM

During this talk, we will consider the large population limit of a binary branching particle system with Moran type interactions introduced recently: this is a model where particles evolve, reproduce and die independently and, with a probability that may depend on the configuration of the whole system, the death of a particle may trigger the reproduction of another particle, while a branching...

10. H. Ammari : 50 ans d'ondes au CMAP

9/12/24, 12:00 PM

Les ondes ont été et continuent d'être un domaine de recherche majeur au CMAP. L'objectif de cette présentation est de retracer l'histoire des ondes au CMAP et de présenter les derniers développements dans ce domaine.

11. J. Josse : Leveraging causal inference to generalize trial results to diverse population.

9/12/24, 2:10 PM

Randomized Controlled Trials (RCTs) are pivotal in evidence-based medicine, estimating average treatment effects by avoiding confounding factors. However, concerns about RCT limitations—strict eligibility criteria, real-world impracticality, and small sample sizes—threaten their generalization to diverse populations. In this talk, I will first present transportability methods by integrating...

12. N. Touzi : Martingale Distributionally Robust Sensitivity

9/12/24, 2:50 PM

Distributionally robust optimization studies the worst deviation of an evaluation functional on the Wasserstein ball centered at the model of interest. We derive explicit sensitivity analysis under marginal and martingale constraints which provide first order hedge against model risk.

13. C. Dapogny : Optimisation de la forme des régions portant les conditions aux limites d’un problème physique

9/12/24, 4:00 PM

Très généralement, l'optimisation de formes vise à optimiser le design d'un domaine du plan ou de l'espace au regard d'un objectif et en respectant certaines contraintes, exprimés comme des fonctions du domaine.

Dans les applications, ces fonctions dépendent de la forme par la solution d'une équation aux dérivées partielles décrivant la physique du problème en jeu, qui est complémentée...

14. E. Moulines : Solving Bayesian Inverse Problems Using Denoising Diffusion Models

9/12/24, 4:40 PM

Solving Bayesian Inverse Problems Using Denoising Diffusion Models

joint work with: Alain Oliviero-Durmus, Yazid Janati-El-Idrissi (post-doc), Badr Moufad (PhD), Mehdi Abou El Qassime (PhD), Ahmed Ghorbel (Ing), Lisa Bedin (Ing), Ecole polytechnique & FX-Conseil, J. Olsson, KTH, S. Le Corff, Sorbonne Université.
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The growing interest in the use of Denoising Diffusion Models (DDMs) as...

15. Séance d'interventions historiques : Jean-Claude Nédélec, Claire Mouradian, Geo Boléat, Jeanne Bailleul, Nicole El Karoui, Laurence Halpern, Marc Schoenauer, Mohamed Jaoua, Jean-François Colonna, Robert Brizzi, Éric Bonnetier, François Jouve, et al.

9/12/24, 5:50 PM

16. R. Douc : Sampling by auxiliary target distributions: from the teleportation algorithm to the importance sampling Markov chain.

9/13/24, 9:30 AM

This review presentation brings together several works conducted in collaboration with Alain Durmus, Jimmy Olsson, Aurélien Enfroy, Charly Andral, Christian Robert, and Yazid Janati.

In this presentation, we will introduce the teleportation algorithm and the importance sampling algorithm by Markov chains. These two algorithms share the common principle of obtaining a chain targeting a...

17. A. Veber : Modéliser le développement d’un champignon filamenteux

9/13/24, 10:10 AM

Les champignons filamenteux forment une très large famille d’espèces ayant un rôle important dans le fonctionnement de nombreux écosystèmes. Ils se développent spatialement grâce à la croissance et à la multiplication de filaments (aussi appelés hyphes) qui permettent l’absorption et le partage de nutriments et d’autres molécules chimiques. Dans cet exposé, on commencera par présenter un...

18. A. Chambolle : Discrete to continuous crystalline curvature flow

9/13/24, 11:20 AM

In this joint work with Daniele DeGennaro (CEREMADE, Parma) and Massimiliano Morini (Parma) we study a fully space and time discrete implicit approximation of the curvature flow, for a surface tension defined by pairwise interactions on the discrete lattice (with bounded range). We study the convergence as the space and time steps go to zero (with different possible regime) and find,...