Mardi 30 Janvier


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Mardi 30 Janvier
Heure: 12:30 - 13:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Decomposition methods for quadratic programming
Description: Emiliano Traversi The purpose of this talk is to present two decomposition methods for quadratic problems. First, we propose a methodological analysis on a family of reformulations combining Dantzig-Wolfe decomposition and Quadratic Convex Reformulation principles for binary quadratic problems. As a representative case study, we apply them to a cardinality constrained quadratic knapsack problem. Secondly, we analyze a simplicial decomposition like algorithmic framework that handles convex quadratic programs in an effective way. In particular, we propose two tailored strategies for solving the master problem and we describe a few techniques for speeding up the solution of the pricing problem. We report extensive numerical experiments on both real-world and generic quadratic programs.
Heure: 14:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: A panorama on real solutions of polynomial systems, illustrated via the RAGLib Maple package
Description: Mohab Safey El Din
Heure: 15:00 - 18:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Aspects énumératifs et bijectifs des cartes combinatoires
Description: Wenjie Fang Les cartes combinatoires, étant un modèle riche, portent plusieurs aspects : algébrique, géométrique, bijective, ... Dans cet exposé, je présente un ensemble de résultats et de connexions dans le domaine de l'énumération des cartes, obtenus à travers des aspectsdifférents. Nous verrons comment utiliser les outils algébrique, comme caractères du groupe symétrique et équations fonctionnelles, à énumérer les cartes. Nous verrons aussi comment étudier les autres objets dans la combinatoire, ici les intervalles du treillis deTamari, à travers de l'aspect bijectif des cartes.
Heure: 16:30 - 18:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: A unified framework for notions of algebraic theory
Description: Soichiro Fujii Universal algebra uniformly captures various algebraic structures, by expressing them as equational theories or (abstract) clones. The ubiquity of algebraic structures in mathematics has also given rise to several variants of universal algebra, such as symmetric and non-symmetric operads, clubs, and monads. In this talk, I will present a unified framework for these cousins of universal algebra, or notions of algebraic theory.

First I will explain how each notion of algebraic theory can be identified with a certain monoidal category, in such a way that theories correspond to monoids. Then I will introduce a categorical structure underlying the definition of models of theories. In specific examples, it often arises in the form of oplax action or enrichment. Finally I will uniformly characterize categories of models for various notions of algebraic theory, by a double-categorical universal property in the pseudo-double category of profunctors.