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Accueil du site > Séminaires et journées internes > Séminaires de Probabilités-Statistiques > Séminaires PS 2018-2019

Séminaires PS 2018-2019



    • Mardi 29 janvier 11:30-12:30 - Catherine Donati - LMV (UVSQ)

      Fluctuations des vecteurs propres associées aux outliers de matrices de Wigner déformées

      Résumé : Lorsque on perturbe additivement une matrice de Wigner, certaines valeurs propres peuvent se détacher du reste du spectre : les "outliers". On s’intéressera aux fluctuations de ces outliers et des vecteurs propres associés.

      Lieu : Bâtiment Fermat - salle 2107

    • Mardi 5 février 11:30-12:30 - Michael Wallner - Université de Bordeaux

      Periodic Pólya Urns and Asymptotics of Triangular Young tableaux

      Résumé : Pólya urns are urns where at each unit of time a ball is drawn uniformly at random and is replaced by some other balls according to its colour. We introduce a more general model : The replacement rule depends on the colour of the drawn ball and the value of the time mod p.
      Our key tool are generating functions, which encode all possible urn compositions after a certain number of steps. The evolution of the urn is then translated into a system of differential equations and we prove that the moment generating functions are D-finite. From these we derive asymptotic forms of the moments. When the time goes to infinity, we show that these periodic Pólya urns follow a rich variety of behaviours : their asymptotic fluctuations are described by a family of distributions, the generalized Gamma distributions, which can also be seen as powers of Gamma distributions.
      Furthermore, we establish some enumerative links with other combinatorial objects, and we give an application for a new result on the asymptotics of Young tableaux : This approach allows us to prove that the law of the lower right corner in a triangular Young tableau follows asymptotically a product of generalized Gamma distributions. This is joint work with Cyril Banderier and Philippe Marchal.

      Lieu : bâtiment Fermat, en salle 2107

    • Mardi 12 février 11:30-12:30 - Charles Tillier - Telecom ParisTech

      Estimation in semi-parametric transformation boundary regression models

      Résumé : Boundary regression models naturally arise in many applications for instance when analysing auctions or records but also in production frontiers and image analysis. Before fitting a regression model it is very common to transform the response variable to gain effciency in the statistical inference. In this talk, we will consider parametric transformations that induce independence of the error distribution from the points of measurements. In such a context, if the transformation of the response is monotone, the attractive feature is that one may recover the original functional dependence in an easy manner. The main purpose of this talk is to investigate the consistency of an estimator based on a minimum distance approach in the context of nonparametric regression models with one-sided errors. In particular, we estimate the transformation parameter and give mild model assumptions under which the estimator is consistent, for both random covariates and fixed design points. The small sample behavior will be shown in a simulation study using the so-called Yeo-Johnson transformations.

      Lieu : Bâtiment Fermat, en salle 2107

    • Mardi 19 février 11:30-12:30 - Adrien Mazoyer - UQAM (Université du Québec à Montréal)

      Titre à venir

      Résumé : Résumé à venir

      Lieu : Bâtiment Fermat - salle 2107

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Les séminaires ont lieu le mardi, bâtiment Fermat, en salle 2107 à 11h30.

Contact : Alexis Devulder et Julien Worms

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Probabilités Statistiques