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.
The contact process with fitness on Galton-Watson trees.
Abstract: The contact process is a simple model for the spread of an infection in a structured population. We consider a variant of the contact process, where vertices are equipped with a random fitness representing inhomogeneities among individuals. In this inhomogeneous contact process, the infection is passed along an edge with rate proportional to the product of the fitness values of the vertices on either end. We assume that the underlying population structure is given by a Galton-Watson tree. Recent works by Huang/Durrett and Bhamidi...
Árboles generadores en grafos aleatorios I
Abstract: En 2015, Kahn conjeturó que para todo ∆ ∊ ℕ, existe un C > 0 tal que para toda secuencia de árboles (Tn)_{n in ℕ}, donde Tn es un árbol en n vértices con ∆(Tn) ≤ ∆, la probabilidad de que el grafo aleatorio G(n,Clogn/n) contenga Tn tiende a 1 cuando n tiende al infinito. Montgomery en el artículo “Spanning trees in random graphs” de 2019, demostró que esta conjetura es cierta. Además, demostró que G(n,Clogn/n) es universal para árboles con grado máximo acotado. En este seminario, veremos un caso específico de este...
Inverse scattering for critical semilinear wave equations.
Abstract: In inverse scattering ione attempts to find the properties of a medium by making remote observations. It has applications in physics, geophysics, medical imaging, non-destructive evaluation of materials. Radar and sonar are examples of inverse scattering methods that are used routinely nowadays. In this case we consider the inverse problem of determining the nonlinearity for critical semilinear wave equations. This is joint work with A, Sa Barreto and Y. Wang.
Large ranking games with diffusion control & Optimal control of the Sweeping Process with a non-smooth moving set.
Title : Large ranking games with diffusion control. Abstract : We consider a symmetric stochastic differential game where each player can control the diffusion intensity of an individual dynamic state process. The players whose states at a deterministic finite time horizon are among the best α ∈ (0, 1) of all states receive a fixed prize. In order to find an equilibrium, we first focus on the version of this game where the number of players tend to infinity. Within the mean field limit version of the game we compute an explicit equilibrium, a...
Toward Elimination of Infectious Diseases with Mobile Screening Teams: HAT in the DRC.
Abstract: In pursuit of Sustainable Development Goal 3 “Ensure healthy lives and promote well-being for all at all ages,” considerable global effort is directed toward elimination of infectious diseases in general and Neglected Tropical Diseases in particular. For various such diseases, the deployment of mobile screening teams forms an important instrument to reduce prevalence toward elimination targets. There is considerable variety in planning methods for the deployment of these mobile teams in practice, but little understanding of their...
Desarrollo de la competencia argumentativa: Tensiones percibidas por profesores de matemáticas chilenos en relación con las pruebas estandarizadas nacionales.
RESUMEN En este estudio investigamos las tensiones percibidas por profesores chilenos de matemáticas entre el desarrollo de la habilidad de argumentar propuesto por el currículum y las evaluaciones estandarizadas nacionales, así como sus consecuencias en el aula. Realizamos veintiún entrevistas semiestructuradas con profesores de primaria y secundaria de las regiones Quinta y Metropolitana, y un análisis temático de los datos obtenidos para identificar patrones y temas recurrentes. Nuestros resultados dan cuenta de la falta de...
Multiplicidad de soluciones por cambios de magnitud.
Abstract: Estudiaremos las soluciones radialmente simétricas del problema Δu+f(u)=0,x∈RN,N>2,lim|x|→∞u(x)=0. Veremos que podemos generar nuevas soluciones del problema si introducimos cambios bruscos en la magnitud de la función f. Usando esto construiremos funciones f, definidas por partes, tales que el problema tiene cualquier número pre-determinado de soluciones.
Número cromático de grafos de distancia exacta.
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.
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.
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...
