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.
Uniquely ergodic subshifts over compactifications of the naturals
RESUMEN: In this talk, we will discuss one-dimensional substitution subshifts over (infinite) compact alphabets and their dynamical properties. As a motivating class, we will focus on shifts generated by a parametrised family of substitutions on certain compactifications of the natural numbers. We will provide a general checkable condition for unique ergodicity that relies on compactness properties of the substitution operator, which the analogue of the substitution matrix for infinite alphabets.
An SDE perspective on stochastic convex optimization.
Abstract: We analyze the global and local behavior of gradient-like flows under stochastic errors towards the aim of solving convex optimization problems with noisy gradient input. We first study the unconstrained differentiable convex case, using a stochastic differential equation where the drift term is minus the gradient of the objective function and the diffusion term is either bounded or square-integrable. In this context, under Lipschitz continuity of the gradient, our first main result shows almost sure weak convergence of the...
Analysing necessary optimality conditions for a time optimal control problem in Wasserstein spaces.
Abstract: We are interested in developing necessary optimality conditions in the form of a Pontryagin maximum principle for the minimal time Bolza optimal control problem with constraints in the final time. In this problem, the dynamic is given by a non-local continuity equation in the Wasserstein space of probability measures, the set of controls are taken in open-loop form and the set of constraints is represented by functional inequalities applied to the terminal time. To this end, we relate the main challenges of this problem from which a...
Determinando la fiabilidad de instrumentos de observación para la enseñanza y el aprendizaje mediante la Teoría de la Generalizabilidad
Resumen: En la presentación daré una breve visión general sobre la medición de la calidad de la enseñanza con calificaciones de observadores, que se han utilizado ampliamente en la investigación sobre la eficacia educativa durante la última década. A continuación, presentaré un marco estadístico que ayuda a dar sentido a los datos resultantes de la observación en el aula, denominado Teoría de la Generalizabilidad (TG). Ambas partes de la presentación estarán repletas de ejemplos de datos reales procedentes de proyectos de...
Undestanding the APS boundary condition for the zero modes of the Dirac operator.
Abstract: How many zero modes (states with zero energy) are there of the Dirac operator with magnetic field in two dimensions? This question was answered by Aharonov and Casher in 1979 for the case of plane. They showed that this number is given by the flux of the magnetic field, more precisely the integer part of it. Moreover, the zero modes are chiral, aligning with the direction of the magnetic field. We investigate the same problem for the case of a plane wih holes considering the Atiyah–Patodi–Singer (APS) boundary condition...
SIR model with social gatherings.
Abstract: The classic susceptible-infected-recovered (SIR) model, introduced by Kermack and McKendrick in 1927, is a simple system of ODEs governing the spread of an infectious disease in a large population. It is based on the assumption that the disease is transmitted via pairwise interactions between infected and susceptible individuals. In this talk, we propose an extension to this model, whose underlying infection mechanism consists of individuals attending randomly generated social gatherings, leading to potentially many new infections....
Topo-isomorfismos de subshifts irregulares de Toeplitz para grupos residualmente finitos.
RESUMEN: Para cada grupo contable residualmente finito G se construyen ejemplos de subshifts irregulares de Toeplitz en {0,1}^G que son topo-isomorfos a su factor maximal equicontinuo. Para obtener este resultado se establecen condiciones suficientes para que un subshift de Toeplitz tenga medidas invariantes como puntos límites de medidas invariantes periódicas sobre {0,1}^G Posteriormente, se construyen arreglos de Toeplitz cuyo subshift asociado satisface tales condiciones para tener medidas invariantes y con esto poder garantizar que son...
Singular limits arising in mechanical models of tumor growth.
Abstract: The mathematical modelling of cancer has been increasingly applying fluid-dynamics concepts to describe the mechanical properties of tissue growth. The bio-mechanical pressure plays a central role in these models, both as the driving force of cell movement and as an inhibitor of cell proliferation. In this talk, I will present how it is possible to build a bridge between models that have different pressure-velocity or pressure-density relations. In particular, I will focus on the inviscid limit from a visco-elastic model to a...
“Estimación Del Disconfort Térmico En La Ciudad De Santiago Mediante Modelación Espacio – Temporal De Índices Termales Durante El Periodo Estival De Los Años 2010 – 2020”
Resumen: Debido a la variabilidad en la configuración urbana en la ciudad de Santiago de Chile durante los últimos años, es probable que aumente la población expuesta a mayores niveles de estrés térmico durante los días más calurosos de verano. Para abordar este problema de salud pública, este trabajo propone una metodología para representar la variación espacial y temporal de tres índices de estrés térmico en Santiago. A partir de datos meteorológicos y productos satelitales MODIS se espacializan series de tiempo de variables ambientales...
Online learning with consistency oracle.
Abstract: A binary classification game is being played between a learner and an adversary. At each round, the adversary selects a natural number x and the learner has to predict its label h(x). Is there a bound on the number of mistakes made by the learner, assuming that h comes from some class H? Littlestone gave a learning algorithm which achieves an optimal mistake bound d, provided H has a certain combinatorial property. However, Littlestone’s algorithm is believed to be computationally demanding. Can we have a feasible strategy...
