Noticias en español
“SNOWCOP: potenciando Copernicus para mejorar el monitoreo del deshielo en los Andes”
En el seminario se mostrará cómo SNOWCOP aprovecha el potencial del programa Copernicus integrando sus abundantes flujos de datos en un enfoque innovador de reconstrucción de nieve. Además, se destacará el papel crucial del Ecosistema del Espacio de Datos de Copernicus (CDSE) en el procesamiento eficiente y a gran escala de estos datos. Esto permitirá generar mapas diarios sin precedentes, de alta resolución (50 m), sobre la cantidad de agua equivalente en nieve (SWE) y las tasas de deshielo en los Andes extratropicales, cubriendo un periodo de más de dos décadas.
Read MoreCellular automata and Percolation on groups.
Resumen: a classical theorem of Gilman shows that every cellular automaton over the integers satisfies a strong dichotomy with respect to any iid Bernoulli process: either almost all configurations are sensitive to initial conditions or it is almost everywhere equicontinuous. If instead of the integers we consider an arbitrary finitely generated group, we will show that there is a strong connection between the triviality of the percolation threshold and the validity of this dichotomy. Using this connection, we will show that Gilman’s dichotomy holds on a countable group if and only if...
Read MoreChromatic threshold via combinatorial convexity, and beyond.
Abstract: We establish a novel connection between the well-known chromatic threshold problem in extremal combinatorics and the celebrated (p,q)-theorem in discrete geometry. In particular, for graphs with bounded clique number and certain natural density condition, we prove a (p,q)-theorem for the dual of its maximal independent sets hypergraph. Our result strengthens those of Thomassen and Nikiforov on the chromatic threshold of cliques. We further show that the graphs under study in fact have `bounded complexity’ in the sense that they are blow-ups of constant size graphs with the same...
Read MoreOpen dynamics on subshifts of finite type.
RESUMEN: Dynamical systems can be broadly classified into closed and open systems. In a (traditional) closed system, the orbit of a point lies in the state space for all time, whereas in an open system, the orbit of a point may eventually escape from the state space through a hole. The notion of open dynamical systems was introduced by Pianigiani and Yorke in 1979, motivated by the dynamics of a ball on a billiard table with pockets. It has attracted the attention of researchers since then especially due to its wide applications.
Read MoreEstabilidad Lipschitz en un problema inverso para un operador parabólico semi-discreto.
RESUMEN: En esta presentación, se abordará un problema inverso para una ecuación parabólica semi- discreta, donde el objetivo es identificar el término en el lado derecho de la ecuación (la fuente) a partir de mediciones de la solución en un tiempo intermedio y dentro de un subdominio espacial. A partir de este resultado, se puede establecer una estimación de estabilidad para la función potencial cuando esta depende únicamente del espacio. Se presentará una nueva estimación de Carleman en el contexto semi-discreto, cuya dependencia del parámetro está determinada por el tamaño de la malla....
Read MoreSampling tree-weighted balanced graph partitions in polynomial time.
Abstract: When judging the fairness of a political redistricting map, it is useful to be able to generate a large ensemble of “random” alternative maps. Formally, this is a graph partitioning problem. The objective is to output random partitions of the vertex set into k equal-sized pieces inducing connected subgraphs. Numerous algorithms have been developed to sample either exactly or approximately from the so-called “spanning tree distribution,” where each partition is weighted by the product of the numbers of spanning trees in each part. However, none of these...
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