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Nombre de programmes trouvés : 747
Cours magistraux

le (1h29m6s)

Robert Young - Quantitative geometry and filling problems (Part 3)

Plateau's problem asks whether there exists a minimal surface with a given boundary in Euclidean space. In this course, we will study related problems in broader classes of spaces and ask what the asymptotics of filling problems tell us about the geometry of surfaces in groups and spaces. What do minimal and nearly minimal surfaces look like in different spaces, and how is the geometry of surfaces related to the geometry of the ambient space? Our main examples will arise from geometric group theory, including nilpotent groups and symmetric spaces.
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Cours magistraux

le (1h28m36s)

Robert Young - Quantitative geometry and filling problems (Part 5)

Plateau's problem asks whether there exists a minimal surface with a given boundary in Euclidean space. In this course, we will study related problems in broader classes of spaces and ask what the asymptotics of filling problems tell us about the geometry of surfaces in groups and spaces. What do minimal and nearly minimal surfaces look like in different spaces, and how is the geometry of surfaces related to the geometry of the ambient space? Our main examples will arise from geometric group theory, including nilpotent groups and symmetric spaces.
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Cours magistraux

le (1h28m21s)

Sylvain Maillot - An introduction to open 3-manifolds (Part 2)

W. Thurston's geometrization program has lead to manyoutstanding results in 3-manifold theory. Thanks to worksof G. Perelman, J. Kahn and V. Markovic, D. Wise, and I. Agol among others, compact 3-manifolds can now beconsidered to be reasonably well-understood.By contrast, noncompact 3-manifolds remainmuch more mysterious. There is a series of examples,beginning with work of L. Antoine and J. H. C. Whitehead,which show that open 3-manifolds can exhibit wildbehavior at infinity. No comprehensive structure theoryanalogous to geometrization à la Thurston is currently availablefor these objectsIn these lectures, we will focus on two aspects of the subject:(1) constructing interesting examples, and(2) finding sufficientconditions ...
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Label UNT Conférences

le (1h28m11s)

Production de sens et informatique

" Comprendre c'est comprendre autrement " H. G. Gadamer Au début de l'été 2000, sur les murs d'une ville, deux affiches, deux affiches réelles : - La première, affichée dans des bars ou des boîtes de nuit, porte sur un fond totalement noir, en grosses lettres grises l'inscription suivante : " Le problème avec le dernier verre c'est que c'est parfois le dernier " - La deuxième, affichée sur les murs d'une commune de banlieue, plus complexe, représente un petit chien, genre roquet regardant les passants et portant dans sa mâchoire un journal plié dont seul le titre est partiellement ...
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Cours magistraux

le (1h27m31s)

Gilles Courtois - The Margulis lemma, old and new (Part 1)

The Margulis lemma describes the structure of the group generated by small loops in the fundamental group of a Riemannian manifold, thus giving a picture of its local topology. Originally stated for homogeneous spaces by C. Jordan, L. Bieberbach, H. J. Zassenhaus, D. Kazhdan-G. Margulis, it has been extended to the Riemannian setting by G. Margulis for manifolds of non positive curvature. The goal of these lectures is to present the recent work of  V. Kapovitch and B. Wilking who gave a sharp version of the Margulis lemma under the assumption that the Ricci curvature is bounded below. Their method ...
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Cours magistraux

le (1h27m21s)

Gilles Courtois - The Margulis lemma, old and new (Part 3)

The Margulis lemma describes the structure of the group generated by small loops in the fundamental group of a Riemannian manifold, thus giving a picture of its local topology. Originally stated for homogeneous spaces by C. Jordan, L. Bieberbach, H. J. Zassenhaus, D. Kazhdan-G. Margulis, it has been extended to the Riemannian setting by G. Margulis for manifolds of non positive curvature. The goal of these lectures is to present the recent work of  V. Kapovitch and B. Wilking who gave a sharp version of the Margulis lemma under the assumption that the Ricci curvature is bounded below. Their method ...
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Cours magistraux

le (1h26m57s)

Yoshihiro Tonegawa - Analysis on the mean curvature flow and the reaction-diffusion approximation (Part 3)

The course covers two separate but closely related topics. The first topic is the mean curvature flow in the framework of GMT due to Brakke. It is a flow of varifold moving by the generalized mean curvature. Starting from a quick review on the necessary tools and facts from GMT and the definition of the Brakke mean curvature flow, I will give an overview on the proof of the local regularity theorem. The second topic is the reaction-diffusion approximation of phase boundaries with key words such as the Modica-Mortola functional and ...
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Cours magistraux

le (1h26m53s)

Thomas Richard - Lower bounds on Ricci curvature, with a glimpse on limit spaces (Part 4)

The goal of these lectures is to introduce some fundamental tools in the study of manifolds with a lower bound on Ricci curvature. We will first state and prove the laplacian comparison theorem for manifolds with a lower bound on the Ricci curvature, and derive some important consequences : Bishop-Gromov inequality, Myers theorem, Cheeger-Gromoll splitting theorem. Then we will define the Gromov-Hausdorff distance between metric spaces which will allow us to consider limits of sequences of Riemannian manifolds, along the way we will prove ...
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Cours magistraux

le (1h26m53s)

J-B Bost - Theta series, infinite rank Hermitian vector bundles, Diophantine algebraization (Part2)

In the classical analogy between number fields and function fields, an Euclidean lattice (E,∥.∥) may be seen as the counterpart of a vector bundle V on a smooth projective curve C over some field k. Then the arithmetic counterpart of the dimension h0(C,V)=dimkΓ(C,V) of the space of sections of V is the non-negative real number h0θ(E,∥.∥):=log∑v∈Ee−π∥v∥2. In these lectures, I will firstly discuss diverse properties of the invariant h0θ and of its extensions to certain infinite dimensional generalizations of Euclidean lattices. Then I will present ...
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