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.
Stability of Stochastic Gradient Descent on Nonsmooth Convex Losses.
Abstract: Uniform stability is a notion of algorithmic stability that bounds the worst case change in the model output by the algorithm when a single data point in the dataset is replaced. An influential work of Hardt, Recht & Singer (ICML’16) provides strong upper bounds on the uniform stability of the stochastic gradient descent (SGD) algorithm on sufficiently smooth convex losses. These results led to important progress in understanding of the generalization properties of SGD and several applications to differentially private...
Intermediate entropy property: old and new.
ABSTRACT: A dynamical system verifying the intermediate entropy property is one such that any value between 0 and the topological entropy is realized as the measure-theoretical entropy of some ergodic measure. In this talk I will present an overview of the main results involving this property, taking as a starting point a conjecture of Katok and ending by a potpourri of recent results.
Some qualitative properties of Lane-Emden type systems.
Abstract: In this talk we discuss some symmetry and unique continuation results for systems of elliptic partial differential equations of Lane-Emden type. As an application, we obtain uniqueness of positive solutions in the subcritical regime, and nonexistence of nontrivial radial solutions in the critical and supercritical cases. Some of our results hold for Pucci’s fully nonlinear operators.
Imágenes Sentinel en la gestión de riesgos naturales: Procesamiento InSAR
Participación en Linea: http://vcespresso.redclara.net/@352109705c115cdd511fb968f9f4ff86# Use Explorer, Firefox o Safari.
Rumor Spreading in Random Hyperbolic Graphs.
Abstract: We analyze several variants of the following randomized broadcast algorithm (a.k.a.~rumor spreading process) on Random Hyperbolic Graphs (RHG). At the beginning, only one node from the giant component (largest connected component) of the RHG is informed. Then, in each round, each informed node chooses a neighbor uniformly and independently at random and pushes the information to it. We give precise estimates (in terms of the RHG’s parameters) for the number of steps this algorithm takes to inform every node in the giant...
Epi-convergence, asymptotic analysis and stability in set optimization problems.
Abstract: We study the stability of set optimization problems with data that are not necessarily bounded. To do this, we use the well-known notion of epi-convergence coupled with asymptotic tools for set-valued maps. We derive characterizations for this notion that allows us to study the stability of vector and set type solutions by considering variations of the whole data (feasible set and objective map). We extend the notion of total epi-convergence to set-valued maps. * This work has been supported by Conicyt-Chile under project FONDECYT...
Incorporación de TICs en formación inicial de profesores de matemática y su impacto en la visualización: el caso de GeoGebra.
RESUMEN Este estudio de caso investiga el impacto que tiene la incorporación de herramientas tecnológicas digitales en las habilidades de visualización matemática y en programas de formación inicial. Informa sobre la influencia del uso del software matemático dinámico GeoGebra en la promoción del aprendizaje matemático en educación secundaria y su impacto en las concepciones que tienen los profesores sobre la enseñanza y el aprendizaje de la disciplina. En particular, describe cómo los applets creados en el entorno GeoGebra -diseñados y...
Crystallization of point configurations to the Square Lattice in 2D.
Abstract: We consider minimum-energy configurations x_1, …, x_N in euclidean space, minimizing the energy given by the sum of V( |x_i-x_j| ) for all pairs of distinct indices i,j, with V an interaction potential. Recent breakthroughs (Viazovska Ann. Math. 2017, Cohn-Kumar-Miller-Radchenko-Viazovska Ann. Math. 2017) led to a proof in arXiv:1902.05438 that special lattices in dimensions 8 and 24 form “universally optimal configurations”, i.e. optimize our energy at fixed density for a large class of V’s. This was...
Maximal Quadratic-Free Sets.
Abstract: The intersection cut paradigm is a powerful framework that facilitates the generation of valid linear inequalities, or cutting planes, for a potentially complex feasible set S of an optimization problem. The key ingredient in this construction is an S-free set: a convex zone whose interior does not intersect S. Ideally, such S-free set would be maximal inclusion-wise, as it would generate a deeper cutting plane. In the case of integer programming, maximal lattice-free sets (i.e., when S corresponds to the integer lattice) have...
