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.

 

Scaling limit of the heavy-tailed ballistic deposition model with p-sticking.

Event Date: Aug 31, 2022 in Seminario de Probabilidades de Chile, Seminars

Abstract: Ballistic deposition is a classical model for interface growth in which unit blocks fall down vertically at random on the different sites of  and stick to the interface at the first point of contact, causing it to grow. We consider an alternative version of this model in which the blocks have random heights which are i.i.d. with a heavy (right) tail, and where each block sticks to the interface at the first point of contact with probability  (otherwise, it falls straight down until it lands on a block belonging to the interface). We...

On large solutions for fractional Hamilton-Jacobi equations.

Event Date: Aug 25, 2022 in Differential Equations, Seminars

Abstract: In this talk I will report some multiplicity results for large solutions of fractional Hamilton-Jacobi equations posed on a bounded domain, subject to exterior Dirichlet conditions. We construct large solutions using the method of sub and supersolutions, following the classical approach of J.M. Lasry and P.L. Lions for second-order equations with subquadratic gradient growth. We identify two classes of solutions: the one coming from the natural scaling of the problem; and a one-parameter family of solutions, different from the...

Árboles generadores en grafos densos II.

Event Date: Aug 25, 2022 in Seminario de Grafos, Seminars

Abstract: En el último seminario vimos un resultado de Komlós, Sárközy y Szemerédi de 1995 sobre la existencia de árboles generadores de grado máximo acotado en grafos densos. Este resultado fue mejorado en 2001 por los mismos autores, quienes demostraron que se puede encontrar árboles generadores de grado máximo O(n/log n) en grafos densos.   Recientemente, Kathapurkar y Montgomery presentaron una generalización de este resultado para grafos dirigidos. A diferencia de los resultados anteriores, la demostración de esta generalización no...

Multidimensional Apportionment Through Discrepancy Theory. & Determination of functions by the metric slope.

Event Date: Aug 24, 2022 in Optimization and Equilibrium, Seminars

Speaker 1: Víctor Verdugo Title: Multidimensional Apportionment Through Discrepancy Theory. Abstract: Deciding how to allocate the seats of a house of representatives is one of the most fundamental problems in the political organization of societies, and has been widely studied over already two centuries. The idea of proportionality is at the core of most approaches to tackle this problem, and this notion is captured by the divisor methods, such as the Jefferson/D’Hondt method. In a seminal work, Balinski and Demange extended the...

Solidarity Cover Problem.

Event Date: Aug 24, 2022 in ACGO, Seminars

Abstract: This work started with a real-world problem where the task was to partition a set of locations into disjoint subsets such that each subset is spread in a way that it covers the whole set with a certain radius. This made us formalizing the following problem which we call Solidarty Cover Problem. Given a finite set S, a metric d, and a radius r, and a number of partitions m. We define a subset C of S to be an r-cover if B(C,r)=S. The Solidarity Cover Problem is the problem of determining whether there exist m disjoint r-covers. We...

A multiple time renewal equation for neural assemblies with elapsed time model.

Event Date: Aug 23, 2022 in Differential Equations, Seminars

Abstract: We introduce and study an extension of the classical elapsed time equation in the context of neuron populations that are described by the elapsed time since last discharge. In this extension we incorporate the elapsed since the penultimate discharge and we obtain a more complex system of integro-differential equations. For this new system we prove convergence to stationary state by means of Doeblin’s theory in the case of weak non-linearities in an appropriate functional setting, inspired by the case of the classical elapsed...

Árboles generadores en grafos densos I.

Event Date: Aug 18, 2022 in Seminario de Grafos, Seminars

Abstract: Dados dos grafos H y G un problema central en teoría de grafos extremales es determinar condiciones globales en G que garantizan la existencia de una copia de H en G. Un ejemplo de resultado en esa dirección es el Teorema de Dirac, que afirma que si G es un grafo en nvértices con grado mínimo al menos n/2, entonces existe una copia del ciclo en n vértices en G. En este seminario vamos a estudiar la relación entre el grado mínimo de G y la existencia de copias de diferentes árboles generadores de G. Más específicamente, vamos a...

A random walk in Number Theory.

Event Date: Aug 17, 2022 in Seminario de Probabilidades de Chile, Seminars

Abstract:  Ver pdf 

Prophet Inequalities via the Expected Competitive Ratio.

Event Date: Aug 17, 2022 in ACGO, Seminars

Abstract: We consider prophet inequalities under general downward-closed constraints. In a prophet inequality problem, a decision-maker sees a series of online elements and needs to decide immediately and irrevocably whether or not to select each element upon its arrival, subject to an underlying feasibility constraint. Traditionally, the decision-maker’s expected performance has been compared to the expected performance of the prophet, i.e., the expected offline optimum. We refer to this measure as the Ratio of Expectations (or, in short,...