Noticias en español
Seminars appear in decreasing order in relation to date. To find an activity of your interest just go down on the list. Normally seminars are given in English. If not, they will be marked as Spanish Only.
Opening Pandora’s Box: the Correlated Case.
Abstract: Pandora’s Box models optimization problems where the input consists of stochastic random variables, but the uncertainty can be removed (i.e. reveal the exact value of a variable) by paying an extra price. Our goal is to maximize (or minimize) the price of the variable chosen minus (resp. plus) the cost we paid to learn the exact instantiations of the variables. All previous work on this class of problems assumes that different random variables in the input are distributed independently. Until recently nothing was known for the...
Minimally implicit Runge-Kutta methods: relativistic resistive magnetohydrodynamic equations and neutrino M1 transport equations.
Abstract: In this talk I will present the minimally implicit Runge-Kutta methods. I will show their application in two different hyperbolic systems of equations with stiff source terms. On one hand, these methods have been sucessfully applied in the evolution of the resistive relativistic magnetohydrodynamic equations following Komissarov (2007) approach. On the other hand, these schemes have been also sucessfully applied in the evolution of the neutrino transport equations within the M1 closure approximation, and used in supernovae...
Un enfoque desde la teoría espectral no autónoma para un problema de estabilidad asintótica global no uniforme: Caso triangular vía uniformización.
Abstract: En esta charla comenzaremos introduciendo la Conjetura de Markus-Yamabe en el contexto autónomo, la cual corresponde a un problema de estabilidad asintótica de ecuaciones diferenciales ordinarias. Luego, identificaremos los conceptos que necesitamos para establecer dicha conjetura en el contexto no autónomo, dando paso así al planteamiento de la conjetura en un contexto no autónomo. Adicionalmente, se mostrará que la conjetura es verificada para sistemas unidimensionales, para cierto tipo de sistemas no lineales y para una familia...
Recent progress on tree packings.
Abstract:We say that a graph H decomposes a graph G if the edges of G can be partitioned into edge-disjoint copies of H. In 1976, Ringel conjectured that any tree of order n+1 decomposes the complete graph on 2n+1 vertices. Recently Montgomery, Pokrovskiy and Sudakov presented a proof of this conjecture for large n. In this talk, we will study the techniques used by Montgomery, Pokrovskiy and Sudakov to prove Ringel’s conjecture.
Lifting Apportionment Methods to Weighted Fair Division.
Abstract: We study the problem of fairly allocating indivisible items to agents with different entitlements, which captures, for example, the distribution of ministries among political parties in a coalition government. This setting (known as weighted fair division) constitutes a generalization of the well-studied apportionment problem, and we present two approaches for lifting apportionment methods to weighted fair division. In the first part of the talk, we focus on additive valuations and show that picking sequences derived from divisor...
Convergence Rate of Nonconvex Douglas-Rachford splitting via merit functions, with applications to weakly convex constrained optimization.
Abstract: We analyze Douglas-Rachford splitting techniques applied to solving weakly convex optimization problems. Under mild regularity assumptions, and by the token of a suitable merit function, we show convergence to critical points and local linear rates of convergence. The merit function, comparable to the Moreau envelope in Variational Analysis, generates a descent sequence, a feature that allows us to extend to the non-convex setting arguments employed in convex optimization. A by-product of our approach is an ADMM-like method for...
Máximo restringido de puentes brownianos no intersectantes.
Resumen: Para un sistema de N puentes Brownianos no intersectantes en [0,1] , se considera M(p,N) la altura máxima alcanzada por el camino superior en el intervalo [0,p] . Bajo un reescalamiento adecuado, M(p,N) converge en distribución, a medida que, N converge a infinito a una familia de distribuciones que interpola entr e las distribuciones de Tracy-Widom para los Ensembles Ortogonales y Unitarios Gaussianos. También se sabe que, para N fijo, M(1,N) se distribuye como el mayor valor propio de una matriz aleatoria extraída del Ensemble...
¿Qué hacen las educadoras de párvulos para enseñar matemáticas? Un análisis de las tareas, estrategias e interacciones.
RESUMEN Las habilidades matemáticas tempranas juegan un rol importante en el desempeño escolar de niñas, niños y jóvenes, ya que marcan diferencias en el ritmo y nivel de aprendizaje. En esta presentación se mostrarán los resultados de una investigación doctoral que tuvo por objetivo caracterizar las prácticas de enseñanza de las educadoras de párvulos en momentos de instrucción matemática. A través de un enfoque metodológico mixto, se estudiaron las tareas matemáticas, las estrategias e interacciones que las educadoras...
Linear and non-linear stability of collisionless many-particle systems on black hole exteriors.
Abstract: I will present upcoming linear and non-linear stability results concerning the asymptotic behavior of collisionless many-particle systems on black hole exteriors. On the one hand, I will discuss decay properties for solutions to the massive Vlasov equation on Schwarzschild spacetime. On the other hand, I will discuss an asymptotic stability result for the exterior of Schwarzschild as a solution to the Einstein–massless Vlasov system, assuming spherical symmetry. I will explain the use of hyperbolic dynamics to obtain decay in time...
Distorsión en grupos de difeomorfismos.
Abstract: esta charla discutiremos el concepto de distorsión en grupos. Un elemento de un grupo finitamente generado se dice distorsionado si la métrica de la palabra de sus potencias crece sublineal. Comenzaremos dando una breve introducción, dando un par de ejemplos y luego daremos un par de aplicaciones. Terminaremos planteando y discutiendo una pregunta propuesta por Andrés Navas.
