Noticias en español
Acciones Por Difeomorfismos de Clase C¹ de los Grupos Baumslag-Solitar en Compactos Son Afines
RESUMEN: Los grupos Baumslag-Solitar BS(m,n) generan un interés dado la variedad en sus propiedades algebraicas y su comportamiento dinámico. De hecho, C. Bonatti, A. Navas, I. Monteverde y C. Rivas mostraron que ciertos grupos solubles (entre ellos BS(1,n)) solamente pueden actuar de manera afín en [0,1] cuando es por difeomorfismos de clase C¹. El motivo de esta charla es revisitar resultados de la dinamica 1-dimensional en acciones de grupos BS(m,n) y probar que en intervalos compactos las acciones por difeomorfismos de los grupos BS(m,n) (que no están incluidos en el trabajo de BMNR) son...
Read MoreHiring under uncertainty and competition: variations of the secretary problema.
Abstract: In this talk, we study some variations of the Secretary Problem. In the Secretary Problem, an employer sees a sequence of candidates. Each time a new candidate arrives, the employer makes an irrevocable choice on whether to hire based only on the relative ranking of the candidates seen so far. The employer tries to maximize the probability of hiring the best. It is known that the optimal strategy hires the best with probability 1/e. We consider an infinite arrival regime. This allows us to apply a lemma characterizing the number of “promising candidates” in any given time interval....
Read MorePartition Regularity for Quadratic Equations in Number Fields.
RESUMEN: An equation is partition regular over its domain if, for any finite coloring of that domain, there exists a monochromatic nontrivial solution. In this talk, we will review the background of this topic, focusing on the ergodic theoretic tools used to tackle such problems and present a recent joint work with A. Koutsogiannis, A. Ferré Moragues and W. Sun, concerning the partition regularity problem of quadratic equations over some number fields.
Read MoreConvergence Rates for Stochastic Proximal and Projection Estimators
Abstract: In this talk, we discuss explicit convergence rates for the stochastic smooth ap-proximations of infimal convolutions introduced and developed in [2, 3]. In particular,we quantify the convergence of the associated barycentric estimators toward prox-imal mappings and metric projections. We prove a dimension-explicit √δ bound, with explicit constants for the proximal mapping, in the ρ-weakly convex (possibly nonsmooth) setting, and we also obtain a dimension-explicit √δ rate for the metric projection onto an arbitrary convex set with nonempty interior. Under additional regularity,...
Read MoreBeating Greedy Asymptotically for Weighted k-Matroid Intersection
Abstract: Greedy is one of the most widely used algorithmic paradigms, both in practice and in theory. Its success is classically explained by matroid theory: whenever the underlying optimization problem has a matroid structure, Greedy is optimal. Greedy also extends to problems involving multiple matroids, but its performance guarantee deteriorates to 1/k, where k is the number of matroids. For Weighted k-Matroid Intersection, Greedy has long been the asymptotically best-known algorithm. In this talk, I will survey recent progress that improves on Greedy for Weighted k-Matroid Intersection...
Read MoreEvolutionary graph theory.
Abstract: What does the coronavirus epidemic have in common with fake news on social media? They are both examples of real-world phenomena in which something (a virus, or the news) is spreading over a graph (a contact network, or a social network). In this talk, we will introduce some extremely simplified random processes that model how things could propagate through graphs, and we will investigate how the outcomes (e.g. “who wins” and “how long it takes”) depend on the graph structure, and on the little details of the underlying random process. Along the way, we will...
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