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.
Acoplamiento inter-placas y Potencial Sísmico en el Lapso Sísmico de Atacama (Chile): Descartando una tajada rígida en los Andes.
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.
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.
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
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.
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.
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.
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.
Scaling limit of the heavy-tailed ballistic deposition model with p-sticking.
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...
Árboles generadores en grafos densos II.
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...
On large solutions for fractional Hamilton-Jacobi equations.
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...
