Noticias en español
Randomized block-coordinate descent beyond gradient global Lipschitz continuity
Abstract: Randomized block-coordinate algorithms are recognized to furnish efficient iterative schemes for addressing large-scale problems, especially when the computation of full derivatives entails substantial memory requirements and computational efforts. Classically, the convergence analysis of these methods relies on a standard assumption of global Lipschitz continuity of partial gradients of differentiable functions. This compromises its applicability to situations where gradient Lipschitz continuity is violated, for instance, in nonnegative matrix factorization or recovery of signals...
Read MoreUnderstanding encoder–decoder structures in machine learning using information measures.
Abstract: We present a theory of representation learning to model and understand the role of encoder–decoder design in machine learning (ML) from an information-theoretic angle. We use two main information concepts, information sufficiency (IS) and mutual information loss to represent predictive structures in machine learning. Our first main result provides a functional expression that characterizes the class of probabilistic models consistent with an IS encoder–decoder latent predictive structure. This result formally justifies the encoder–decoder forward stages many modern ML architectures...
Read MoreAnalyzing the (k-)swap neighborhood for makespan scheduling.
Abstract: Analyzing the behavior of local search methods has received considerable attention over the last two decades. One interesting question is how the simplest form of local search, i.e., iterative improvement, behaves w.r.t. a certain neighborhood both in quality of the solution as well as number of iterations needed to obtain a local optimal solution. In this talk, we consider the basic scheduling problem in which n jobs need to be scheduled on m identical machines so as to minimize the makespan, i.e., the completion time of the last job. Finn and Horowitz (1979) showed that the...
Read MoreDatos de observación de la Tierra para evaluar el impacto del cambio climático en los cambios de uso de suelo en Chile
En el seminario se abordará cómo las sequías prolongadas, intensificadas por el cambio climático, están transformando la cobertura terrestre en Chile. La investigación presentada analiza el impacto de los cambios acumulativos en la oferta y demanda de agua —en distintas escalas temporales— sobre la productividad vegetal y el uso de suelo, en el contexto de la megasequía que afecta al país desde 2010.
Read MoreDecidability 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 two aperiodic minimal substitutive subshifts. The...
Read MoreComplejidad 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 particular, en el contexto de grupos ordenables...
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