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.
Compartmental Models for Infectious Diseases: Structure, Intervention, and Applications.
Abstract: Compartmental models have become a fundamental tool for understanding the spread of infectious diseases and evaluating the potential impact of public health interventions. By dividing populations into epidemiological classes and describing transitions between them, these models provide a flexible mathematical framework for studying disease dynamics across a wide range of contexts. In this talk, I will present an overview of compartmental modeling for infectious diseases, including model formulation, qualitative analysis,...
Poisson-Voronoi percolation in high dimensions.
Resumen: We consider a Poisson point process with constant intensity in $ \mathbb{R}^d $ and independently color each cell of the resulting random Voronoi tessellation black with probability $ p $. The critical probability $ p_c(d) $ is the value for $ p $ above which there exists almost surely an unbounded black component and almost surely does not for values below. In this talk I aim to give an overview of the model and sketch some ideas of a proof that $ p_c(d)=(1+o(1)) e d^{-1} 2^{-d} $, as $ d\to\infty $. We also obtain the...
Rainbow trees and graceful labellings.
Abstract: A tree T on n vertices is said to be graceful if there exists a bijective labelling f of its vertices to the set {1,2,…,n} such that the values of |f(x)-f(y)| are pairwise distinct over all edges xy in E(T), or equivalently, such that the set {|f(x)-f(y)| : xy in E(T)} has size exactly n-1. The longstanding graceful tree conjecture, posed by Rósa in the 1960s, asserts that every tree is graceful. We prove an approximate version of this conjecture by showing that every tree T on n vertices has a bijective labelling f of its...
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)...
Hiring 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...
Partition 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.
Evolutionary 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...
Beating 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...
An orbit around quasi-trasitive graphs
Abstract: A graph is called quasi-transitive if it has finitely many orbits under automorphism. I will present some recent advances on quasi-transitive graphs, especially in the planar and minor-free cases. I will also talk about some related recent work with Agelos Georgakopoulos and Bobby Miraftab.
