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.
Experimentation in Two-Sided Marketplaces: The Impact of Interference.
Abstract: Marketplace platforms use experiments (also known as “A/B tests”) as a method for making data-driven decisions about which changes to make on the platform. When platforms consider introducing a new feature, they often first run an experiment to test the feature on a subset of users and then use this data to decide whether to launch the feature platform-wide. However, it is well documented that estimates of the treatment effect arising from these experiments may be biased due to the presence of interference driven by the substitution...
Explainable Affirmative Action.
Ver pdf, adjunto.
Distance evolutions in growing preferential attachment graphs.
Abstract: In this talk we will study the evolution of the graph distance between two fixed vertices in dynamically growing random graph models. More precisely, we consider preferential attachment models with parameters such that the asymptotic degree distribution has infinite second moment. First, we grow the graph until it contains $t$ vertices, then we sample $u_t, v_t$ uniformly at random from the largest component and study the evolution of the graph distance as the surrounding graph grows. This yields a stochastic process in $t’\ge...
Competition and Recall in Selection Problems.
Abstract: In this talk, I will present an extension of the prophet inequality problem to a competitive setting. At every period, a new sample from a known distribution arrives, which is publicly observed. Then, two players simultaneously decide whether to pick an available value or to pass and wait until the next period (ties are broken uniformly at random). As soon as a player gets one sample, he leaves the market, and his payoff is the value of the sample. In a first variant, namely no recall case, the agents can only bid in each period for...
A limit law for the most favorite point of a simple random walk on a regular tree.
We consider a continuous-time random walk on a regular tree of finite depth and study its favorite points among the leaf vertices. We prove that, for the walk started from a leaf vertex and stopped upon hitting the root, as the depth of the tree tends to infinity the maximal time spent at any leaf converges, under suitable scaling and centering, to a randomly-shifted Gumbel law. The random shift is characterized using a derivative-martingale-like object associated with the square-root local-time process on the tree.
Existence of solutions on the critical hyperbola for a pure Lane-Emden system with Neumann boundary conditions.
Abstract: I will present some recent results obtained in collaboration with A. Pistoia and H. Tavares for a Lane-Emden system on a bounded regular domain with Neumann boundary conditions and critical nonlinearities. We show that, under suitable conditions on the exponents in the nonlinearities, least-energy (sign-changing) solutions exist. In the proof we exploit a dual variational formulation which allows to deal with the strong indefinite character of the problem, and we establish a compactness condition which is based on a new Cherrier...
Detección Espectral de Especies Nativas a partir de datos Hiperespectrales HySpex y LiDAR en Bosques Templados al Sur de Chile.
Resumen: Al sur de Chile a 28 km de Valdivia, se encuentra el Parque Oncol. Este parque se ubica entre el Océano Pacífico y el Santuario de la Naturaleza Carlos Anwandter, el cual representa un Área de Alto Valor de Conservación (AAVC), de gran importancia ecológica para Arauco. Sus bosques de tipo templado lluvioso son un verdadero refugio para especies endémicas de flora y fauna, algunas de ellas en peligro de extinción actualmente. El objetivo de este estudio fue caracterizar la biodiversidad del Parque Oncol, mediante la detección...
Non-existence results for an eigenvalue problem involving Lipschitzian nonlinearities with non-positive primitive and applications.
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Generalized formulations for the traveling salesman problem.
Abstract: The traveling salesman problem is a widely studied classical combinatorial problem for which there are several integer linear formulations. In this work, we consider the Miller-Tucker-Zemlin (MTZ) formulation. First, we argue that the choice of some parameters of this formulation is arbitrary and, therefore, there is a family of formulations of which MTZ is a particular case. We analyze this family, noting that in general the formulations involved are not comparable to each other and there is no one that dominates the rest. Then,...
Nonlocal Aggregation-Difusion Equations: entropies, gradient flows, phase transitions and applications.
Abstract: his talk will be devoted to an overview of recent results understanding the bifurcation analysis of nonlinear Fokker-Planck equations arising in a myriad of applications such as consensus formation, optimization, granular media, swarming behavior, opinion dynamics and nancial mathematics to name a few. We will present several results related to localized Cucker-Smale orientation dynamics, McKean-Vlasov equations, and nonlinear difusion Keller-Segel type models in several settings. We will show the existence of continuous or...
