Seminars

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.

 

Hunting transient astrophysical events with the ALeRCE community broker.

Event Date: Jun 03, 2024 in Seminars, SIPo (Seminario de Investigadores Postdoctorales)

Summary: The Automatic Learning for the Rapid Classification of Events (ALeRCE) is a Chilean-led astronomical alert broker, and one of the seven brokers selected to receive the full alert stream from the Rubin Observatory. Since 2019 ALeRCE has been ingesting the public stream from the Zwicky Transient Facility, which contains hundreds of thousands of alerts per night, providing classifications and visualization for the astronomical objects detected. In this talk I describe the ALeRCE project and its different science cases, showing how it...

Problemas Respecto a la Invarianza del Espectro de Dicotomia No Uniforme.

Event Date: Jun 03, 2024 in Dynamical Systems, Seminars

RESUMEN: En su tesis doctoral, S. Siegmund demostró que si dos sistemas eran cinemáticamente similares, entones tenían el mismo espectro de dicotomía exponencial. En los ultimos años se han propuesto muchas generalizaciones a este resultado para abarcar las dicotomias no uniformes. En esta charla demuestro que estas generalizaciones no se siguen realmente, ya que se basan en hipótesis que no se alcanzan de manera general. Junto con ello, presento ejemplos explícitos y además propongo una alternativa más débil de la invarianza espectral,...

Desarrollo de algoritmos de machine learning para generación de mapas LCLU de Latinoamérica y el Caribe para el proyecto CopernicusLAC Chile

Event Date: May 31, 2024 in Ciclo de Seminarios conjuntos CopLAC-Chile, Seminars

A partir del cruce de múltiples productos internacionales de LCLU se generan datasets diferidos para el entrenamiento de algoritmos de machine learning especializados hacia los diferentes climas presentes en Latinoamérica y el Caribe. El producto resultante se contrasta con aquellos ya disponibles y se establecen los pasos a seguir para la obtención de resultados más precisos y la inclusión de una mayor cantidad de coberturas de suelo en las siguientes iteraciones del proyecto Land Cover del Centro Regional CopernicusLAC Chile.

A sequential Stackelberg game for dynamic inspection problems.

Event Date: May 29, 2024 in ACGO, Seminars

Abstract:  This talk considers a game where an inspection authority must verify that a set of operators adhere to a certain rule. The inspector has time to inspect only a few operators, and this must be done sequentially. The operators disclose the sequence of inspections as they occur. We will discuss variants of this sequential game. The talk focuses on the mathematical structure of the set of equilibria of this inspection game, where the inspector is a Stackelberg leader and is capable of performing exactly two inspections. A static and...

Event Date: May 28, 2024 in Seminario de Grafos, Seminars

Abstract: On 14/5 I gave a talk revolving around the fat minor conjecture. On 15/5 a paper appeared on Arxiv claiming to disprove it. I will report on this new development and I will attempt to offer a comprehensive view of the new questions that it raises, such as “Is this for real?” and “What now?”.

Regla de las fases de Gibbs para potenciales Hölder en la familia de Manneville-Pomeau.

Event Date: May 27, 2024 in Dynamical Systems, Seminars

RESUMEN: En esta charla daremos una clasificación de los potenciales Hölder para las dinámicas en la familia de Manneville-Pomeau. Esta clasificación depende de la propiedades termodinámicas de los potenciales. Mostraremos que cuando existen potenciales con transiciones de fase hay dos fases  en el espacio de potenciales, cada fase es un abierto conexo, y la unión de estas dos fases es densa. También mostraremos que estas dos fases tienen una frontera común y que esta frontera es homeomorfa a un subespacio de codimensión 1.

Estudio Comparativo De La Evaluación Antropogénica Y Geogénica De La Concentración De Metales Pesados Y Lábiles En Sedimentos Marinos Superficiales Y Suelos De La Zona Norte De Chile.

Event Date: May 23, 2024 in Seminario CMM MIning, Seminars

Resumen: La investigación, permite la identificación, priorización, jerarquización y evaluación preliminar de la contaminación en zonas muy degradadas ambientalmente y posibilita la determinación de los niveles de los cuales se establecen los límites de inocuidad y peligrosidad en ambientes costeros. El propósito del estudio es elaborar un diagnóstico regional de los suelos y sedimentos marinos del borde costero del norte de Chile con potencial presencia de elementos trazas y metales pesados. El estudio, analiza la potencial...

Attention is Turing Complete.

Event Date: May 22, 2024 in ACGO, Seminars

Abstract:  Alternatives to recurrent neural networks, in particular, architectures based on self-attention, are gaining momentum for processing input sequences. In spite of their relevance, the computational properties of such networks have not yet been fully explored. We study the computational power of the Transformer, one of the most paradigmatic architectures exemplifying self-attention. We show that the Transformer with hard-attention is Turing complete exclusively based on their capacity to compute and access internal dense...

Prophet Inequalities Require Only a Constant Number of Samples.

Event Date: May 15, 2024 in ACGO, Seminars

Abstract:  In a prophet inequality problem, n independent random variables are presented to a gambler one by one. The gambler decides when to stop the sequence and obtains the most recent value as a reward. We evaluate a stopping rule by the worst-case ratio between its expected reward and the expectation of the maximum variable. Because of its connections with resource allocation and posted-price mechanisms, this problem has been intensively studied, and several variants have been introduced. While most of the literature assumes that...

On Wu’s Inequality and the Poisson-Föllmer Process.

Event Date: May 15, 2024 in Seminario de Probabilidades de Chile, Seminars

Resumen:  In the discrete setting the Poisson distribution is a ubiquitous object, as the Gaussian distribution is in the Euclidean setting. In spite of that, it does not satisfy Gross’ log-Sobolev inequality. Nevertheless, Bobkov and Ledoux were able to prove that it satisfies a “modified” version of it, which was subsequently reinforced by Wu. In the first part of this talk we will exhibit a new stochastic proof of Wu’s modified log-Sobolev, via an entropy-minimizing process constructed by Klartag and Lehec, which we call the...