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Nombre de programmes trouvés : 3932
Conférences

le (53m36s)

R. Ghezzi - Volume measures in non equiregular sub-Riemannian manifolds

In this talk we study the Hausdorff volume in a non equiregular sub-Riemannian manifold and we compare it to a smooth volume. First we give the Lebesgue decomposition of the Hausdorff volume. Then we focus on the regular part, show that it is not commensurable with a smooth volume and give conditions under which it is a Radon measure. Finally we give a complete characterization of the singular part. This is a joint work with F. Jean (ENSTA).
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Conférences

le (54m38s)

N. Juillet - Deformation of singular spaces

Gigli and Mantegazza have observed how optimal transport and heat diffusion allow to describe the direction of the Ricci flow uniquely from the metric aspects of Riemannian manifolds. Their goal is to reformulate the Ricci flow so that it also makes sense for metric spaces. I will present investigations and results obtained with Matthias Erbar (univ. Bonn) that concerns some non-Riemannian limits of Riemannian manifolds, in particular the Heisenberg group.
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Conférences

le (1h29m14s)

Du Réel - Guy-Félix Duportail

Au programme de cette rencontre Proto-Philo organisée par la bibliothèque Cuzin de l'Université Paris 1 Panthéon-Sorbonne, Guy-Félix Duportail, maître de conférence en philosophie à l'Université Paris 1, répondait aux questions de Bernard Passavy (doctorant en philosophie à l'Université Paris 1) et Raphaël Ehrsam (maître de conférence en philosophie à l'Université Paris 4), à propos de son ouvrage Du Réel paru aux éditions Hermann en 2017.
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Conférences

le (57m31s)

R. Monti - Excess and tangents of sub-Riemannian geodesics

We present some recent results on the regularity problem of sub-Riemannian length minimizing curves. This is a joint work with A. Pigati and D. Vittone. After introducing the notion of excess for a horizontal curve, we show that at any point of a length minimizing curve excess is infinitesimal at some sequence of scales. This implies the existence of a linear tangent. We also discuss other results related to excess.
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Conférences

le (1h2m0s)

S.Rigot - Besicovitch covering property in sub-Riemannian geometry

The Besicovitch covering property originates from works of Besicovitch about differentiation of measures in Euclidean spaces. It can more generally be used as a usefull tool to deduce global properties of a metric space from local ones. We will discuss in this talk the validity or non validity of the Besicovitch covering property on stratified groups equipped with sub Riemannian distances (Carnot groups) and more generally on graded groups equipped with homogeneous distances. We will illustrate these results with explicit examples in the Heisenberg group. ...
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Conférences

le (58m26s)

Safety Verification of Deep Neural Networks

Deep neural networks have achieved impressive experimental results in image classification, but can surprisingly be unstable with respect to adversarial perturbations, that is, minimal changes to the input image that cause the network to misclassify it. With potential applications including perception modules and end-to-end controllers for self-driving cars, this raises concerns about their safety. This lecture will describe progress with developing a novel automated verification framework for deep neural networks to ensure safety of their classification decisions with respect to image manipulations, for ...
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