naie

Désolé, aucun contenu ne correspond à vos critères.

Séminaire de probabilités et statistiques
The Covariance Matrix Adaptation Evolution Strategy (CMA-ES) is a stochastic derivative-free optimization algorithm designed to solve difficult (e.g., ill-conditioned, multi-modal) optimization problems. In this presentation, I will talk about the recent convergence results that are obtained by studying the stability of a Markov chain defined by the normalization of the state variables of CMA-ES. Even so CMA-ES has been the state-of-the-art algorithm for black-box optimization in moderate dimensions for more than 20 years, this is its first convergence proof. Joint work with Anne Auger and Nikolaus Hansen.

Séminaires systèmes dynamiques et géométrie
Let $(M,g,X)$ be a complete gradient Kähler–Ricci expander with quadratic curvature decay (including all derivatives). Its geometry at infinity is modeled by a unique asymptotic cone, which takes the form of a Kähler cone $(C_0,g_0)$. In this talk, we will show that if there exists a solution to the Kähler–Ricci flow on $M$ that desingularizes this cone, then it necessarily coincides with the self-similar solution determined by the soliton metric $g$. Furthermore, if one perturbs the soliton metric in a suitable manner, the resulting initial data generates an immortal solution to the Kähler–Ricci flow which, after appropriate rescaling, converges to an asymptotically conical gradient Kähler–Ricci expander.

Séminaire de topologie et géométrie algébriques

Séminaire de probabilités et statistiques
Imaginons qu'on joue au démineur sur une grand grille, et qu’on place des mines au hasard avec une densité prescrite. On observe alors une transition de phase (grossière), c’est à dire que si notre densité est en dessous d’un ordre de grandeur critique, alors on peut toujours gagner (et avec un algoithme de complexité linéaire), alors qu’au dessus de cet ordre de grandeur critique, on ne peut jamais gagner, ceci étant dû à l’apparition de motifs ambigus.

Séminaires systèmes dynamiques et géométrie

Séminaire de probabilités et statistiques
Mixed-phenotype acute leukemia (MPAL) is a rare disease with poor prognosis. So far, no standard approach has been established as the “know-how” of MPAL is based only on retrospective analyses performed on small groups of patients. In this talk we describe the Bayesian technique combined with profile likelihood: a statistical technique whose main advantage is the ability to precisely examine the uncertainty of one selected parameter in complex models. We will show the results obtained with fruitful collaboration with the Polish Adult Leukemia Group.

Séminaire de topologie et géométrie algébriques
It is well known that integral lattices in de Rham or rigid cohomology cannot satisfy étale descent. In this talk, I will show some positive results in this direction when considering the tame topology of Hübner--Schmidt. This is a joint work in progress with Kay Rülling and Shuji Saito.

Séminaire 2PMA
TBA

Séminaire de probabilités et statistiques
In this talk, we address the stability problem of the famous Brascamp-Lieb inequality for strictly log-concave probability measures on the Euclidean space. More precisely, if a given function almost satisfies the equality in the BL inequality, is it true that it is close in some sense to the underlying extremal functions? Using a spectral interpretation of the BL inequality, we prove that the distance to the extremal functions in quadratic norm is of order square root of the deficit parameter, and involves the second positive eigenvalue of a convenient diffusion operator we wish to estimate. Our results are illustrated by some examples for which the usual uniform convexity assumption on the potential is relaxed. This is a joint work with M. Bonnefont (Institut de Mathématiques de Bordeaux) and J. Serres (Sorbonne Université).