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.

 

Número cromático de grafos de distancia exacta.

Event Date: Sep 29, 2022 in Seminario de Grafos, Seminars

Abstract: Se presentarán los principales resultados del paper “Chromatic numbers of exact distance graphs” (https://doi.org/10.1016/j.jctb.2018.05.007) El grafo de distancia exacta p de un grafo G=(V,E) es el grafo con el mismo conjunto de vértices que G y entre dos vértices hay una arista si y sólo si estos vértices están a distancia exactamente p en G. Usando la noción de números de coloreos generalizados se encontrarán cotas para el número cromático de grafos de distancia exacta p, separando los casos en que p sea impar y el...

Recursive local amoeba construction.

Event Date: Sep 28, 2022 in ACGO, Seminars

Abstract: Amoeba graphs were born as examples of balanceable graphs, which are graphs that appear in any 2-edge coloring of the edges of a large enough $K_n$ with a sufficient amount of red and blue edges. As they were studied further, interesting aspects were found. An edge replacement $e\to e$ in a labeled graph G means to take an edge e in E(G) and replace it with e’ \in E(\overline{G})\cup \{e\}$. If $G-e+e’$ is isomorphic to $G$ then we say $e\to e’$ is a \emph{feasible edge replacement}. Every edge replacement yields a...

Time periodic solutions for 3D quasi-geostrophic model.

Event Date: Sep 27, 2022 in Differential Equations, Seminars

Abstract: The aim of this talk is to study time periodic solutions for 3D inviscid quasigeostrophic model. We show the existence of non trivial simply-connected rotating patches by suitable perturbation of stationary solutions given by generic revolution shapes around the vertical axis. The construction of those special solutions are done through bifurcation theory. In general, the spectral problem is very delicate and strongly depends on the shape of the initial stationary solutions. More specifically, the spectral study can be related to an...

Acoplamiento inter-placas y Potencial Sísmico en el Lapso Sísmico de Atacama (Chile): Descartando una tajada rígida en los Andes.

Event Date: Sep 26, 2022 in Ciclo de Seminarios quincenales de la Alianza Copernicus-Chile, Seminars

Resumen: “Se presenta una nueva metodología para investigar el grado de acoplamiento (una medida del potencial sismogénico) a lo largo de la interfaz entre placas en zonas de subducción. Aquí, se infiere la deformación y movimientos rígidos de la placa continental de manera conjunta con el grado de acoplamiento entre las placas tectónicas. Las inferencias son constreñidas por mediciones de deformación de la superficie de la corteza terrestre, obtenidas a partir de observaciones de instrumentos del Sistema Global de Navegación por...

Endomorfismos no uniformemente hiperbólicos.

Event Date: Sep 26, 2022 in Dynamical Systems, Seminars

RESUMEN: Voy a presentar ejemplos de endomorfismos del toro que son C^1 robustamente no uniformemente hiperbólicos. Además los ejemplos son establemente ergódicos, y los exponentes de Lyapunov son continuos con respecto al endomorfismo en la topología C^1.

Bayesian Persuasion With Costly Information Acquisition.

Event Date: Sep 21, 2022 in ACGO, Seminars

Abstract: We consider a Bayesian persuasion model in which the receiver can gather independent information about the state at a uniformly posterior-separable cost. We show that the sender provides information that prevents the receiver from gathering independent information in equilibrium. When the receiver faces a lower cost of information, her `threat’ of gathering independent information increases, thus decreasing the sender’s power to persuade. A lower cost of information can also hurt the receiver because the sender may...

Almost triangular Markov chains on ℕ

Event Date: Sep 21, 2022 in Seminario de Probabilidades de Chile, Seminars

Abstract:   A transition matrix U on ℕ is said to be almost upper triangular if U(i,j)≥0⇒j≥i−1, so that the increments of the corresponding Markov chains are at least −1; a transition matrix L on ℕ is said to be almost lower triangular if L(i,j)≥0⇒j≤i+1, and then, the increments of the corresponding Markov chains are at most +1. In this talk I will characterise the recurrence, positive recurrence and invariant distribution for the class of almost triangular transition matrices. These results encompass the case of birth and death processes...

Long-time behavior of a sexual reproduction model under the effect of strongly convex selection.

Event Date: Sep 20, 2022 in Differential Equations, Seminars

Abstract: The Fisher infinitesimal model is a widely used statistical model in quantitative genetics that describes the propagation of a quantitative trait along generations of a population subjected to sexual reproduction. Recently, this model has pulled the attention of the mathematical community and some integro-differential equations have been proposed to study the precise dynamics of traits under the coupled effect of sexual reproduction and natural selection. Whilst some partial results have already been obtained, the complete...

The kidney exchange problem: length-constrained cycles and chains optimization on compatibility graphs.

Event Date: Sep 07, 2022 in ACGO, Seminars

Abstract: The kidney exchange problem is a combinatorial optimization problem that arises naturally when implementing centralized kidney exchange programs. Given a directed weighted graph (called the compatibility graph), we aim to find a collection of simple and vertex-disjoint cycles maximizing the total weight of their participating arcs. Because of logistical considerations, a bound k is placed on the length of each possible cycle. We will briefly explain how the problem is polynomially solvable in the cases k = 2 and unbounded k, and why...

Árboles generadores en grafos densos III.

Event Date: Sep 01, 2022 in Seminario de Grafos, Seminars

Abstract: En este seminario seguimos estudiando el artículo Spanning trees in dense directed graphs de Kathapurkar y Montgomery. Más específicamente, veremos cómo encontrar copias de algunos árboles casi-generadores en grafos densos. Además, vamos a ver como el Lema de Regularidad, utilizado en la demostración de otros resultados en el área, es reemplazado por un proceso aleatorio para encontrar la copia del árbol.