Seminars

A (2 + epsilon)-approximation algorithm for preemptive weighted flow time on a single machine.

Event Date: Apr 14, 2021 in ACGO, Seminars

Abstract:  In a recent breakthrough in scheduling, Batra, Garg, and Kumar gave the first constant approximation algorithm for minimizing the sum of weighted flow times. Wiese and I (STOC’21) managed to improve this large unspecified constant to 2 + epsilon. I will give a very graphic presentation of the algorithmic techniques behind this.

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A new proof of Aldous-Broder theorem.

Event Date: Apr 14, 2021 in Seminario Probabilidades CMM, Seminars

Resumen:  The Aldous–Broder algorithm is a famous algorithm used to sample a uniform spanning tree of any finite connected graph G, but it is more general: it states that given a reversible M Markov chain on G started at r and up to the cover time, the tree rooted at r formed by the steps of successive first entrance in each node (different from the root) has a probability proportional to the product of these edges according to M, where the edges are directed toward r. In this talk I will present an extension to the non-reversible case and a new combinatorial proof of this theorem. Based on...

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Un abordaje regional al estudio de la propagación y control del COVID-19 en Chile.

Event Date: Apr 14, 2021 in Seminarios Lectura Papers COVID19, Seminars

Resumen:  Esta charla se centra en un trabajo desarrollado en el marco de mi tesis doctoral, donde pretendo compartirles algunas particularidades presentes en la evolución del virus SARS-Cov2 en las regiones de Chile, en especial para el periodo contemplado entre el 3 marzo al 27 de julio de 2020, teniendo en cuenta las medidas de cuarentena aplicadas a nivel regional antes del Plan Paso a Paso, y que intentamos involucrar en la formulación y descripción de nuestro modelo compartimental,  el cual ajustamos a datos regionales para estimar algunos parámetros. A tales parámetros les realizamos...

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Asymptotic stability manifolds for solitons in the generalized Good Boussinesq equation.

Event Date: Apr 15, 2021 in Differential Equations, Seminars

Abstract: In this talk, I shall consider the generalized Good-Boussinesq model in one dimension, with power nonlinearity and data in the energy space $H^1\times L^2$. I will present in more detail the long-time behavior of zero-speed solitary waves, or standing waves. By using virial identities, in the spirit of Kowalczyk, Martel, and Muñoz, we construct and characterize a manifold of even-odd initial data around the standing wave for which there is asymptotic stability in the energy space.

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Expansión sublineal en grafos.

Event Date: Apr 12, 2021 in Seminario de Grafos, Seminars

Resumen: En esta charla introduciremos los aspectos básicos de los grafos con expansión sublineal y su uso en problemas extremales. En particular, mostraremos una aplicación sencilla para encontrar subdivisiones del grafo completo en grafos con grado promedio relativamente bajo. Acá el link al zoom: https://uchile.zoom.us/j/83539034403?pwd=NlZ6UGwzNndpZHNZNThGSzViMldLdz09 password 624=05

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Invariant Family of Leaf measures and The Ledrappier-Young Property for Hyperbolic Equilibrium States.

Event Date: Apr 12, 2021 in Dynamical Systems, Seminars

ABSTRACT: Let be a Riemannian, boundaryless, and compact manifold with , let be a () diffeomorphism of , and let be a Hölder continuous potential on . We construct an invariant and absolutely continuous family of measures (with transformation relations defined by ), which sit on local unstable leaves. We present two main applications. First, given an ergodic homoclinic class , we prove that admits a local equilibrium state on if and only if is “recurrent on ” (a condition tested by counting periodic points), and one of the leaf measures gives a positive measure to a set of...

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