Seminars

Fredholm groupoids

Event Date: Jan 22, 2020 in Differential Equations, Seminars

Resume : In many cases, the study of linear partial differential equations on a singular manifold can be related to that of a Lie groupoid whose action generates the (pseudo)differential operators of interest. Obtaining Fredholm conditions for these operators leads to the definition of Fredholm groupoids as recently introduced by Carvalho, Nistor and Qiao and also studied by Côme. I will introduce theses objects and give examples to illustrate the notion of Fredholm groupoids.  

Quantum Mean Field Asymptotics and Multiscale Analysis

Event Date: Jan 22, 2020 in Differential Equations, Seminars

Abstract: In a joint work with Z. Ammari, and F. Nier, we study how multiscale  analysis and quantum mean field asymptotics can be brought together. In  particular we study when a sequence of one-particle density matrices has  a limit with two components: one classical and one quantum. The introduction of “separating quantization for a family” provides a  simple criterion to check when those two types of limit are well  separated. We also give examples of explicit computations of such limits, and how to check that the separating assumption is satisfied. In this talk we will...

On the propagation of regularity for solutions of the Zakharov-Kuznetsov equation & Weakly coupled bound states of Pauli operators

Event Date: Nov 30, 1999 in Differential Equations, Seminars

Le Jugement Majoritaire, une nouvelle théorie du choix social

Event Date: Jan 15, 2020 in Other Areas, Seminars

Abstract: Le Jugement Majoritaireest une nouvelle théorie du choix social applicable à toute prise de décision collective, établie par les chercheurs du CNRS Michel Balinski et Rida Laraki à partir de 2006. En adoptant une toute nouvelle perspective du vote pour tenter de répondre au théorème d’impossibilité d’Arrow, elle résout les paradoxes de l’élection constatés par Condorcet et Arrow. L’électeur vote en évaluant individuellement tous les candidats, à partir d’une échelle commune et ordinale du mentions (par ex. Très bien, Bien, Assez bien, Passable,...

The median rule in judgement aggregation (joint work with Klaus Nehring).

Event Date: Jan 15, 2020 in Other Areas, Seminars

Abstract: I will first briefly introduce social choice theory in general. I will then move onto the subfield of judgement aggregation, and discuss some recent research on this topic. In a judgement aggregation problem, we begin with a set K of logically interconnected propositions, called issues. A view is an assignment of a truth-value to each issue in K. However, not all views are admissible; some may violate the logical relationships between the different issues in K. Suppose that each individual voter has a logically consistent view; we want to aggregate these individual views together...

On the unreasonable effectiveness of the Sinkhorn algorithm

Event Date: Jan 14, 2020 in Seminario Aprendizaje de Máquinas, Seminars

Abstract: This talk concerns Sinkhorn algorithm, broadly understood as the iterative scaling of a matrix that realizes the solution of an entropy regularized linear program subjected to row and column constraints. I will present new theoretical and applied results that demonstrate the effectiveness of this procedure in two contexts: first, Sinkhorn algorithm implements the solution of an entropy regularized version of optimal transport. I will show this regularization substantially improves sample complexity over the unregularized case, a result that helps explain the popularity of this...