Séminaires : Séminaire de Géométrie

Equipe(s) : gd,
Responsables :L. Hauswirth, P. Laurain, R. Souam, E. Toubiana
Email des responsables :
Salle : 1013
Adresse :Sophie Germain

Archive avant 2014

Hébergé par le projet Géométrie et Dynamique de l’IMJ-PRG



Orateur(s) Mircea PETRACHE - PUC - Chili,
Titre Uniform measures and manifolds all of whose curvatures are constant
Horaire13:30 à 15:00

A uniform measure in Euclidean space R^d is a measure with respect to which balls B(x,r) with center x in the support, are assigned mass dependent of r and independent of the choice x. For example any invariant measure with respect to a subgroup of the isometry group of R^d is uniform, and called a homogeneous measure. However we also have a few exotic examples of non-homogeneous uniform measures, such as the volume measure of the "light cone" {x^2+y^2+z^2=w^2} in R^4.
This class of measures was first studied by David Preiss as the crucial ingredient of his 1987 proof of the Besicovitch conjecture. The complete classification of uniform measures remains a difficult open problem, even restricted to ambient dimension d=2. I will detail the known classification of 1-dimensional uniform measures in R^d for general d, for which, in joint work with Paul Laurain, we show that they are constituted of disjoint unions of helices or of toric knots, or equivalently, of analytic curves all of whose curvatures are constant.

AdresseSophie Germain