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.
Comparison of arm exponents in planar FK-percolation.
Resumen: FK-percolation is a generalisation of Bernoulli percolation that was found to be related to a wide range of other models in statistical mechanics, including the Ising model and the six-vertex model. In this talk, we will focus on the specific case of critical planar FK-percolation in the continuous phase transition regime. In this setting, the model exhibits properties similar to those of critical planar Bernoulli percolation; in particular, the Russo-Seymour-Welsh theory applies and the model is conjectured to be conformally...
Decidability of the isomorphism problem between constant-shape substitutions.
Abstract: An important question in dynamical systems is the classification, i.e., to be able to distinguish two isomorphic dynamical systems. In this work, we focus on the family of multidimensional substitutive subshifts. Constant-shape substitutions are a multidimensional generalization of constant-length substitutions, where any letter is assigned a pattern with the same shape. We prove that in this class of substitutive subshifts, under the hypothesis of having the same structure, it is decidable whether there exists a factor map between...
Complejidad Boreliana Para Acciones de Grupos.
RESUMEN La teoría descriptiva de conjuntos es un área originada a inicios del siglo XX gracias al trabajo de los franceses Baire, Borel y Lebesgue. De esta teoría, nacen los conceptos de ‘equivalencia orbital’ y ‘complejidad boreliana’ como una herramienta para clasificar acciones de grupos sobre espacios Polacos. A través de esta charla introduciremos los conceptos antes mencionados junto a los distintos niveles de complejidad para finalizar con resultados y aplicaciones a la teoría de grupos ordenables; en ...
Chromatic 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...
“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...
Estabilidad 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...
Cellular 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...
Open 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.
Truthful Budget Aggregation: Beyond Moving-Phantom Mechanisms.
Abstract: We study a budget-aggregation setting in which a number of voters report their ideal distribution of a budget over a set of alternatives, and a mechanism aggregates these reports into an allocation. Ideally, such mechanisms are truthful, i.e., voters should not be incentivized to misreport their preferences. For the case of two alternatives, the set of mechanisms that are truthful and additionally meet a range of basic desiderata (anonymity, neutrality, and continuity) exactly coincides with the so-called moving-phantom mechanisms,...
Generative Social Choice
The mathematical study of voting, social choice theory, has traditionally only been applicable to choices among a few predetermined alternatives, but not to open-ended decisions such as collectively selecting a textual statement. We introduce generative social choice, a design methodology for open-ended democratic processes that combines the rigor of social choice theory with the capability of large language models to generate text and extrapolate preferences. Our framework divides the design of AI-augmented democratic processes into two...
