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Nombre de programmes trouvés : 33151
Conférences

le (41m33s)

Massoulié - Planting trees in graphs, and finding them back

In this talk we  consider detection and reconstruction of planted structures in Erdős-Rényi random graphs. For planted line graphs, we establish the following phase diagram. In a low density region where the average degree λ of the initial graph is below some critical value λc, detection and reconstruction go from impossible to easy as the line length K crosses some critical value f(λ)ln(n), where n is the number of nodes in the graph. In the high density region λ>λc, detection goes from impossible to easy as K goes from o(\sqrt{n}) to ω(\sqrt{n}), and reconstruction remains impossible so long as K=o(n). We show similar properties for planted D-ary trees. These results are in contrast with the ...
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Conférences

le (42m3s)

Verzelen - Clustering with the relaxed K-means

This talk is devoted to clustering problems. It amounts to partitionning a set of given points or the nodes of a given graph, in such a way that the groups are as homogeneous as possible. After introducing two random instances of this problem, namely sub-Gaussian Mixture Model (sGMM) and Stochastic Block Model (SBM), I will explain how convex relaxations of the classical $K$-means criterion achieve near optimal performances. Emphasis will be put on the connections between the clustering bounds and relevant results in random matrix theory.
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Cours magistraux

le (57m49s)

Tropp 3/9 - Random matrix theory and computational linear algebra

This course treats some contemporary algorithms from computational linear algebra that involve random matrices. Rather than surveying the entire field, we focus on a few algorithms that are both simple and practically useful. We begin with an introduction to matrix concentration inequalities, which are a powerful tool for analyzing structured random matrices. We use these ideas to study matrix approximations constructed via randomized sampling, such as the random features method. As a more sophisticated application, we present a complete treatment of a recent algorithm for solving graph Laplacian linear systems in near-linear time. Some references : 1. Tropp, "An introduction to ...
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Cours magistraux

le (1h21s)

Tropp 4/9 - Random matrix theory and computational linear algebra

This course treats some contemporary algorithms from computational linear algebra that involve random matrices. Rather than surveying the entire field, we focus on a few algorithms that are both simple and practically useful. We begin with an introduction to matrix concentration inequalities, which are a powerful tool for analyzing structured random matrices. We use these ideas to study matrix approximations constructed via randomized sampling, such as the random features method. As a more sophisticated application, we present a complete treatment of a recent algorithm for solving graph Laplacian linear systems in near-linear time. Some references : 1. Tropp, "An introduction to ...
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Entretiens

le (7m40s)

Les mobilités géographiques: un objet sociologique? Pierre LANNOY

Pierre Lannoy est chercheur au centre de recherche METICES de l’Institut de sociologie de l’Université libre de Bruxelles et chargé de cours à la Faculté de philosophie et sciences sociales. Auteur de nombreux articles sur la manière dont la sociologie américaine a traité la question des mobilités spatiales, il est l’auteur en 2019, avec Yoann Demoli, de l’ouvrage Sociologie de l’automobile aux Editions de la Découverte (collection Repères). Manuel de sociologie des mobilités géographiques
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Entretiens

le (10m10s)

Se déplace-t-on de la même manière qu'il y a 20 ans? Jean-Pierre ORFEUIL

Jean-Pierre Orfeuil est professeur émérite d’aménagement à l’Institut d’urbanisme de Paris (IUP) à l’Université Paris-Est. Spécialiste des mobilités urbaines, il a publié de nombreux ouvrages sur la mobilité, dont Accès et mobilités. Les nouvelles inégalités en 2016 (avec F. Ripoll) aux éditions Infolio ou Une approche laïque de la mobilité aux éditions Descartes en 2008.Manuel de sociologie des mobilités géographiques
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