Seminars

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.

 

SIR model with social gatherings.

Event Date: May 18, 2022 in CMM Covid-19 Seminar, Seminars

Abstract: We introduce an extension to Kermack and McKendrick’s classic susceptible-infected-recovered (SIR) model in epidemiology, whose underlying mechanism of infection consists of individuals attending randomly generated social gatherings. This gives rise to a system of ODEs where the force of infection term depends non-linearly on the proportion of infected individuals. Some specific instances yield models already studied in the literature, to which the present work provides a probabilistic foundation. The basic reproduction number...

Closedness under addition for families of quasimonotone operators.

Event Date: May 11, 2022 in Optimization and Equilibrium, Seminars

Abstract:  In this talk we will discuss some results about quasimonotone family of operators. For some notions that are extensions of monotoniticity but not beyond quasimonotonicity like pseudomonotonicity, semistrict quasimonotonicity, strict quasimonotonicity and proper quasimonotonicity, we will discuss systematically when the sum of two operators satisfying one of those properties, inherits the same property. Several examples showing the optimality in some sense of our results, are presented. Join work with: Fabián Flores-Bazán and...

Efficiency and fairness in random resource allocation and social choice.

Event Date: May 11, 2022 in ACGO, Seminars

Abstract: We study efficiency in general collective choice problems when agents have ordinal preferences, and randomization is allowed. We establish the equivalence between welfare maximization and ex-ante efficiency for general domains, and relate ex-ante efficiency with ex-post efficiency, characterizing when the two notions coincide. We also propose a new general notion of fairness that is applicable in any social choice environment, not only in resource allocation. Our results have implications for well-studied mechanisms including random...

Pensamiento matemático creativo: Entornos didácticos que posibilitan su desarrollo en el aula de Enseñanza Básica.

Event Date: May 10, 2022 in Education, Seminars

RESUMEN Desarrollar la creatividad se considera uno de los principales objetivos de la educación matemática. La forma en que los entornos educativos pueden contribuir a potenciar esta capacidad en los estudiantes es un tema de gran interés en el último tiempo. En esta presentación se mostrarán los resultados de una investigación doctoral que estudió la influencia de los entornos didácticos (Sarrazy & Novotná, 2013) en el desarrollo de la creatividad matemática de los estudiantes. Se empleó un diseño metodológico mixto secuencial. En una...

Una nueva visión del Laplaciano fraccionario vía redes neuronales profundas.

Event Date: May 10, 2022 in Differential Equations, Seminars

Abstract:  El Laplaciano fraccionario ha sido fuertemente estudiado durante las últimas décadas. En esta charla presentamos un nuevo enfoque al problema de Dirichlet asociado, usando técnicas recientes de aprendizaje profundo. En efecto, últimamente se ha demostrado que las soluciones aciertas ecuaciones en derivadas parciales se pueden representar de manera estocástica, y aproximar dicha representación mediante redes neuronales profundas, superando la llamada mal dición de la dimensionalidad. Entre estas ecuaciones se encuentran las de tipo...

No hiperbolicidad de polinomios fibrados.

Event Date: May 09, 2022 in Dynamical Systems, Seminars

ABSTRACT: La conjetura de Fatou, de 1920, sobre polinomios hiperbólicos, ha sido de gran interés en las últimas décadas aunque sin resultados concluyentes. Buzzard logró probar que esta conjetura no tiene validez en dimensión 2 compleja. En esta charla probaremos que en una “dimensión intermedia” y con herramientas menos sofisticadas a las usadas por Buzzard, esta conjetura es falsa para polinomios fibrados holomorfos.

Competition processes on hyperbolic non-amenable graphs.

Event Date: May 04, 2022 in Seminario de Probabilidades de Chile, Seminars

Abstract:  We consider two first-passage percolation processes, FPP_1 and FPP_\lambda, spreading with rates 1 and \lambda  respectively, on a graph G with bounded degree.  FPP_1 starts from a single source, while the initial configuration of FPP_\lambda consists of countably many seeds distributed according to a product of iid Bernoulli random variables of parameter \mu on the set of vertices. This model is known as “First passage percolation in a hostile environment” (FPPHE), it was introduced by Stauffer and Sidoravicius as an...

Nonlocal truncated Laplacians: representation formulas and Liouville results.

Event Date: May 03, 2022 in Differential Equations, Seminars

Abstract: We consider some nonlinear extremal integral operators that approximate the, so called, degenerate truncated Laplacians. For these operators we obtain representation formulas that lead to the construction of “fundamental solutions” and  to Liouville type results. Differences with respect to both the local case and the uniformly elliptic framework will be emphasized.

Semi-random process.

Event Date: Apr 27, 2022 in ACGO, Seminars

Abstract: The semi-random graph process is a single-player game that begins with an empty graph on n vertices. In each round, a vertex u is presented to the player independently and uniformly at random. The player then adaptively selects a vertex v and adds the edge uv to the graph. For a fixed monotone graph property, the objective of the player is to force the graph to satisfy this property with high probability in as few rounds as possible. During the talk, we will focus on the following problems: a) perfect matchings, b) Hamilton cycles,...

Optimal design problems for a degenerate operator in Orlicz-Sobolev spaces.

Event Date: Apr 26, 2022 in Differential Equations, Seminars

Abstract: An optimization problem with volume constraint involving the Φ-Laplacian in Orlicz-Sobolev spaces is considered for the case where Φ does not satisfy the natural condition introduced by Lieberman. A minimizer uΦ having non-degeneracy at the free boundary is proved to exist and some important consequences are established like the Lipschitz regularity of uΦ along the free boundary, that the set {uΦ>0} has uniform positive density, that the free boundary is porous with porosity δ>0 and has finite (N−δ)-Hausdorff measure. Under a...