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.

 

COVID-19: Short-term forecast of ICU beds in times of crisis.

Event Date: Jan 27, 2021 in Seminarios Lectura Papers COVID19, Seminars

Abstract:   By early May 2020, the number of new COVID-19 infections started to increase rapidly in Chile, threatening the ability of health services to accommodate all incoming cases. Suddenly, ICU capacity planning became a first-order concern, and the health authorities were in urgent need of tools to estimate the demand for urgent care associated with the pandemic. In this article, we describe the approach we followed to provide such demand forecasts, and we show how the use of analytics can provide relevant support for decision...

On the construction of maximal p-cyclically monotone operators.

Event Date: Jan 20, 2021 in Optimization and Equilibrium, Seminars

Abstract: In this talk we deal with the construction of explicit examples of maximal p-cyclically maximal monotone operators. To the date, there is only one instance of an explicit example of a maximal 2-cyclically monotone operator that is not maximal monotone. We present several other examples, and a proposal of how such examples can be constructed.

Optimization of a Concentrated Solar Power plant.

Event Date: Jan 20, 2021 in Seminarios Lectura Papers COVID19, Seminars

    Abstract This report corresponds to the continuation of another where the characteristics of the parameters and methods of each one of the objects called Parameters, SolarField, Rankine and Reactor were detailed. Here we will present the components of the objective function of the optimization problem described in section 2, which corresponds to the income and costs generated by the concentrated solar power plant for a period of Nyears, as well as the constraints and bounds related to the variables of the problem. Then we...

Eigenvalue splitting of polynomial order for a system of Schrödinger operators with energy-level crossing.

Event Date: Jan 12, 2021 in Differential Equations, Seminars

In this talk I will present recent results on the spectral analysis of a 1D semiclassical system of coupled Schrödinger operators each of which has a simple well potential. Such systems arise as important models in the Born-Oppenheimer approximation of molecular dynamics. Focusing on the cases where the two underlying classical periodic trajectories cross to each other which imply an energy-level crossing, we give Bohr-Sommerfeld type quantization rules for the eigenvalues of the system in both tangential and transversal crossing cases. Our...

Aumentando óptimamente la nodo-conectividad de un ciclo en uno.

Event Date: Jan 07, 2021 in Seminario de Grafos, Seminars

Abstract: “Definimos el problema de “aumentación de conectividad de grafos” de la forma siguiente: La entrada es un grafo G y un conjunto de aristas E, tal que G es k-conexo y G+E es (k+1)-conexo. Y la salida debe ser un subconjunto F de E de tamaño mínimo tal que G+F sea (k+1)-conexo. Este tipo de problemas se enmarcan en el diseño de redes, muy importante en áreas tales como telecomunicaciones y electricidad. Muchos de estos problemas son NP-dificiles, por lo que es necesario diseñar algoritmos de aproximación para atacar...

Casi todos los árboles dirigidos son n-inevitables.

Event Date: Dec 17, 2020 in Seminario de Grafos, Seminars

Resumen: Se mostrará una condición suficiente para ver que un árbol dirigido es n-inevitable, esto se probará a través de un resultado de descomposición de torneos de Kühn, Mycroft y Osthus, y el uso lema de embedding semi-determinista, que nos permite embeber árboles en n-o(1) vértices, finalmente se verá que las condiciones suficientes se cumplen asintótica-casi-seguramente.

Equivalencia orbital fuerte y complejidad factorial en subshifts.

Event Date: Dec 16, 2020 in Dynamical Systems, Seminars

ABSTRACT: Dos sistemas dinámicos topológicos se dicen orbitalmente equivalentes cuando existe un homemorfismo entre los espacios de fase que envía órbitas en órbitas. Dado un subshift minimal, su complejidad factorial es la función $p_X: \N \to \N$ que cuenta el número de cilindros no vacíos de largo $n$. En esta charla discutiremos sobre cómo la complejidad factorial posiblemente restringe las clases de equivalencia orbital (fuerte) para subshifts minimales. Trabajo conjunto con S. Donoso.

Well-quasi-ordering digraphs by the strong immersion relation.

Event Date: Dec 16, 2020 in ACGO, Seminars

Abstract: A well-quasi-ordering is a reflexive and transitive binary relation such that every infinite sequence has a non-trivial increasing subsequence. The study of well-quasi-ordering was stimulated by two conjectures of Vazsonyi in 1940s: trees and subcubic graphs are well-quasi-ordered by the topological minor relation. It is known that the topological minor relation does not well-quasi-order all graphs. Nash-Williams in 1960s introduced the notion of strong immersion and conjectured that the strong immersion relation well-quasi-orders...

Bipartite Ramsey numbers of paths for random graphs.

Event Date: Dec 10, 2020 in Seminario de Grafos, Seminars

    Resumen: Dado dos grafos G y H, decimos que G —> H si para todo 2-coloreo (rojo/azul) de las aristas de G contiene una copia de H monocromática. Sea G(K_k(n),p) un espacio de grafos aleatorios con probabilidad de aristas p, donde K_k(n) es el grafo completo k-partito con n vértices en cada parte. Demostramos que si np va a infinito entonces la probabilidad de que G(K_k(n),p) —>P_(k-1-o(1))n tiende a 1 para k=2,3.

Solitons and multilinear Harmonic Analysis with potentials.

Event Date: Dec 09, 2020 in Differential Equations, Seminars

  Abstract: We study some classes of nonlinear dispersive PDEs with potentials in both 1 and 3 dimensions, motivated by questions on the stability of solitons and topological solitons. Our approach is based on the so-called “distorted Fourier transform” adapted to Schrodinger operators, and the development of multilinear harmonic analysis in this setting. This approach allows us to treat low power nonlinearities and describe the global space-time behavior of solutions, also by capturing singularities in frequency space which may arise...