Différences

Ci-dessous, les différences entre deux révisions de la page.

--- mega:seminaire [2019/12/19 13:52] – [Prochaine séance] Guillaume BARRAQUAND
+++ mega:seminaire [2019/12/19 18:29] – [Prochaine séance] Guillaume BARRAQUAND
@@ Ligne 14: / Ligne 14: @@
 ===== Prochaine séance =====
     * Vendredi **17 janvier**, salle 201
-       * 10h30-12h00: **[[https://webusers.imj-prg.fr/~frederic.klopp/|Frédéric Klopp]]**////\\ Frédéric Klopp
+       * 10h30-12h00: **[[https://webusers.imj-prg.fr/~frederic.klopp/|Frédéric Klopp]]**////\\
-       * 14h00-15h00:  **[[https://www.lpthe.jussieu.fr/~zuber/|Jean-Bernard Zuber]]**////\\
+       * 14h00-15h00:  **[[https://www.lpthe.jussieu.fr/~zuber/|Jean-Bernard Zuber]]**// A review of Horn's problem //\\
+Horn's problem deals with the following question: what can be said about the spectrum of eigenvalues of the sum C=A+B of two Hermitian matrices of given spectrum ? The support of the spectrum of C is now well understood, after a long series of works from  Weyl (1912)  to Horn (1952) to Klyachko (1998) and Knutson and Tao (1999). The problem has also amazing connections with group  theory and the decomposition of tensor product of representations. \\  \\ Comparison with the same problem for real symmetric matrices and the action of the orthogonal group reveals similarities but also unexpected differences... \\ \\ In this talk, after a short introduction to the problem, I’ll  sketch the computation of  the probability distribution function of the eigenvalues of C, when A and B are independently and uniformly distributed on their orbit under the action of the group.\\
+\\ If time permits, I'll also review some  aspects of the connection with representation theory.
        * 15h30-16h30:  **[[http://perso.ens-lyon.fr/adrien.kassel/|Adrien Kassel]]**////\\
@@ Ligne 33: / Ligne 36: @@
     * Vendredi **6 décembre**, séance annulée
     * Vendredi **17 janvier**, salle 201
-       * 10h30-12h00: ////\\
+       * 10h30-12h00: **[[https://webusers.imj-prg.fr/~frederic.klopp/|Frédéric Klopp]]**////\\
        * 14h00-15h00:  **[[https://www.lpthe.jussieu.fr/~zuber/|Jean-Bernard Zuber]]**////\\
        * 15h30-16h30:  **[[http://perso.ens-lyon.fr/adrien.kassel/|Adrien Kassel]]**////\\
     * Vendredi **7 février**, salle 421 le matin, amphi Hermite l'après-midi
-       * 10h30-12h00: ////\\
+       * 10h30-12h00: **[[http://djalil.chafai.net/|Djalil Chafaï]]**////\\
        * 14h00-15h00:  ////\\
        * 15h30-16h30:  ////\\