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.
A Water-Filling Primal-Dual Algorithm for Approximating Non-Linear Covering Problems.
Abstract: Obtaining strong linear relaxations of capacitated covering problems constitute a significant technical challenge even for simple settings. For one of the most basic cases, the Knapsack-Cover (Min-Knapsack) problem, the relaxation based on knapsack-cover inequalities has an integrality gap of 2. These inequalities are exploited in more general problems, many of which admit primal-dual approximation algorithms. Inspired by problems from power and transport systems, we introduce a general setting in which items can be taken...
On the relation between topological entropy and asymptotic pairs.
ABSTRACT: I will present some results that state that under certain topological conditions, any action of a countable amenable group with positive topological entropy admits off-diagonal asymptotic pairs. I shall explain the latest results on this topic and present a new approach, inspired from thermodynamical formalism and developed in collaboration with Felipe García-Ramos and Hanfeng Li, which unifies all previous results and yields new classes of algebraic actions for which positive entropy yields non-triviality of their associated...
The value of observability in dynamic pricing.
Abstract: Research on dynamic pricing has been growing during the last four decades due to its use in practice by a variety of companies as well as the several model variants that can be considered. In particular, we consider the pricing problem where a firm wants to sell one item to a single buyer in order to maximize expected revenues. On one hand, the firm commits to a price function over an infinite horizon. On the other, the buyer has a private value for the item and purchases at the time when his utility is maximized. In our model, the...
Reproduction matrix for an epidemic and lockdowns in a city.
Abstract: We consider an epidemic spreading in a city which is divided geographically into different districts. We introduce the reproduction matrix R = R(i, j) between districts, where R(i, j) is the mean number of individuals in district j infected by an individual from district i. We analyse policies of partial lockdowns of the city, that is of a set of districts, based on the study of matrix R, where rows and columns corresponding to districts in lockdown are set to zero. This schema can also be applied to a country divided into...
Long-time asymptotics for the cubic NLS in 1d.
Abstract: I will discuss the long-time asymptotics of small solutions to the 1d cubic NLS with a potential. Using distorted Fourier transforms, localized dispersive estimates, we obtain the long-time asymptotics for the 1d cubic NLS under very mill assumptions on potentials. This is joint work with Fabio Pusateri.
El pensamiento covariacional de docentes en formación y su impacto en cómo entienden el calentamiento global.
RESUMEN En esta presentación, se discute cómo el pensamiento covariacional de tres docentes en formación emerge mientras trabajan en un problema matemático que explora la conexión entre la contaminación de dióxido de carbono (CO2) y el calentamiento global. También se discuten formas en las que el pensamiento covariacional apoya o limita el entendimiento de dicha conexión. Los docentes en formación fueron entrevistados individualmente mientras trabajaban en el problema matemático. El análisis de las entrevistas reveló que sólo cuando los...
Trazabilidad de proximidad vía Aps. La idea, los desafíos y las preguntas abiertas.
Ciclo de Charlas Explorando la complejidad de las enfermedades infecciosas Trazabilidad de proximidad vía Aps. La idea, los desafíos y las preguntas abiertas. Para participar, solo debe enviar un correo confirmando su interés a sistemascomplejosv (at) gmail.com y se le responderá con el link a la Charla.
Distorted diffeomorphisms and regularity.
ABSTRACT: The goal is to deal with the following question: for a compact manifold M, does there exist a diffeomorphism that is distorted in the group of C^r diffeomorphisms yet undistorted in the group of C^s diffeomorphism, where 1 \leq r < s ? Although the answer seems to be positive, it seems hard to build explicit examples (these diffeomorphisms necessarily have zero entropy). We will provide such examples for the closed unit interval for r = 1 and s = 2. The distortion part of the proof uses standard techniques on centralizers; the...
Topological phase transition as a statistical reconstruction problem.
Abstract: Joint work with C. Garban. KT or topological phase transitions are a type of phase transition discovered by Kosterlitz and Thouless in the ’70s. Models that undergo this phenomenon are typically 2-dimensional and do not have a classical phase transition. In this talk, I will explain this type of phase transition going over the first proof of their existence by Fröhlich and Spencer which relates them to the localisation of random surfaces. Then, I will discuss a new interpretation of this phase transition that arises from the...
