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SEMINARIOS ONLINE

Seminario Online Estefani Moraes Moreira

The concept of hyperbolicity of equilibria for a nonlocal and quasilinear problem

FECHA: 26 DE JULIO DE 2021

HORA:  12:00H

Abstract:

In this talk, we study a dissipative one-dimensional parabolic problem with a nonlocal diffusivity.
We address the hyperbolicity of equilibria in this context, for which linearization procedures are not directly applicable

Seminario Online Anabel Forte Deltell

AnabelForte

Bayes y la búsqueda del modelo perfecto

FECHA: 19 DE JULIO DE 2021

HORA:  12:00H

Abstract:

Entender cómo funciona el mundo que nos rodea y cuáles son las relaciones entre los procesos que tienen lugar en él, ha sido siempre un objetivo primordial para el ser humano. Los modelos matemáticos y estadísticos son una gran herramienta para cumplir con este propósito. Sin embargo, en un mundo en el que el acceso a datos e información es cada vez más fácil, y la capacidad computacional es cada vez mayor, elegir un modelo adecuado se convierte en un gran reto. Por una parte, cabe determinar qué variables están involucradas en un proceso de interés. ¿Está relacionada la temperatura ambiente con el funcionamiento de una placa solar? ¿Puede verse influido el crecimiento de un país por su consumo energético? ¿Qué componentes del ADN están relacionadas con la resistencia a una enfermedad? Por otra parte, será necesario elegir la forma del modelo, las distribuciones probabilísticas o las ecuaciones adecuadas al proceso. Dos tareas nada sencillas para las que existen multitud de aproximaciones. En concreto, en esta charla, daremos un paseo por el mundo de la selección Bayesiana de modelos y los grandes retos que ha supuesto para el desarrollo de la Estadística.

Seminario Online José María Amigó

OLYMPUS DIGITAL CAMERA

Complexity-based permutation entropy

FECHA: 12 DE JULIO DE 2021

HORA:  12:00H

El registro se cerrará 20 minutos antes del inicio del   seminario.

Abstract:

Entropy is a useful concept in many areas of physics and applied mathematics, primarily thermodynamics (where it originated), statistical mechanics, information theory, dynamical systems and data analysis. In the first part of our talk, we will review (i) the Shannon entropy, (ii) the permutation entropy, which is the Shannon entropy in the symbolic representation of real-valued time series via permutations, and (iii) the axiomatic definition of the entropy of probability distributions, which leads to the weaker concepts of generalized entropy, compossable entropy and group entropy.

In the second part, we will focus on the permutation entropy. Although this entropy has proven to be useful in data analysis, its theoretical aspects have remained limited to noiseless deterministic series (i.e., generated by dynamical systems), the main obstacle being the super-exponential growth of visible permutations with length when randomness (also in form of observational noise) is present in the data. To overcome this shortcoming, we take a new approach through complexity classes, which are defined by the asymptotic growth of visible permutations with length. Thus, deterministic processes belong to the exponential class, while usual noisy processes belong to the factorial class. For the processes of each possible class, we will construct a group entropy that is finite and coincides with the conventional permutation entropy on the exponential class. This construction is completely general and can be applied to other situations.

Seminario Online Maria Chiara Pagliarella

maria_chiara.pagliarella

A real sampling strategies for estimating totals and averages on a grid of quadrats: applications to forest surveys

FECHA: 05 DE JULIO DE 2021

HORA:  12:00H

Abstract:

The Reduction of Emissions from Deforestation and forest Degradation (REDD) project was proposed and initiated in 2005. Monitoring of forest cover by statistical methodologies is a key pre-requisite. Forest cover is usually estimated at large scale by spatial sampling strategies, in which the study region is partitioned into polygons of equal size (e.g. quadrats). Then, a sample of N units is selected, aerial photos are provided and visually interpreted to determine the forest cover. In order to incorporate spatial aspect into the design and to account for the presence of spatial autocorrelation among the units, in this paper are compared familiar sampling schemes such as simple random sampling without replacement (SRSWR), one-per-stratum stratified sampling (STR) and systematic sampling (SIS) against ad hoc spatial schemes such as Local Pivotal Method of the first type (LPM1) by Grafström et al. (2012), Generalized Random-Tessellation Stratified Sampling (GRTSS) by Steven and Olsen (2004), Spatially Correlated Poisson Sampling (SCPS) by Grafström (2012), the drawn-by-drawn scheme avoiding the selection of contiguous units by Fattorini (2006) and the Doubly Balanced Spatial Sampling by Grafström and Tillé (2013). A simulation study is performed in order to compare and check the validity of each strategy.

Seminario Online Maria Chiara Pagliarella

maria_chiara.pagliarella

Small area estimation of poverty indicators under partitioned area-level time models

FECHA: 01 DE JULIO DE 2021

HORA:  12:00H

Abstract:

This paper deals with small area estimation of poverty indicators. Small area estimators of these quantities are derived from partitioned time-dependent area-level linear mixed models. The introduced models are useful for modelling the different behaviour of the target variable by sex or any other dichotomic characteristic. The mean squared errors are estimated by explicit formulas. An application to data from the Spanish Living Conditions Survey is given

Seminario Online Luis Orea

image_gallery

Estimating a stochastic epidemic frontier model that controls for undocumented COVID-19 cases with an application to Spain

FECHA: 22 DE JUNIO DE 2021

HORA:  12:00H

Abstract:
We use a stochastic frontier analysis (SFA) approach to model the propagation of the COVID-19 epidemic across geographical areas. The proposed models permit reported and undocumented cases to be estimated, which is important as case counts are overwhelmingly believed to be undercounted. The models can be estimated using only epidemic-type data but are flexible enough to permit these reporting rates to vary across geographical cross-section units of observation. We provide an empirical application of our models to Spanish data corresponding to the initial months of the original outbreak of the virus in early 2019. We find remarkable rates of under-reporting that might explain why the Spanish Government took its time to implement strict mitigation strategies. We also provide insights into the effectiveness of the national and regional lockdown measures and the influence of socio-economic factors in the propagation of the virus.

Seminario Online Ricardo Martínez

FECHA: 14 DE JUNIO DE 2021

HORA:  12:00H

Abstract:

We consider the problem of randomly allocating indivisible units of a resource among agents with conflicting claims on the resource. In the two-agent case, we characterize three focal rules combining axioms reflecting principles of compensation and sacrifice: probabilistic uniform awards, probabilistic uniform losses and probabilistic concede-and-divide. In the general case of n agents, the two uniform rules are characterized adding the axiom of consistency. There is, however, no consistent extension of probabilistic concede-and-divide.

Seminario Online Jordi Castro

An interior-point solver for large block-angular problems and applications

FECHA: 31 DE MAYO DE 2021

HORA:  12:00H

Abstract:

Interior point methods (IPMs) have shown to behave very well in some classes of large-scale structured optimization problems. We will discuss a successful approach for block-angular structures that relies on the combination of Cholesky factorizations and preconditioned conjugate gradients for the normal equations. In the first part of the talk we will outline such specialized IPM, which is implemented in a solver named BlockIP (coded in C/C++). In the second part of the talk we will overview a set of applications where this algorithm outperformed some of the most efficient alternative state-of-the-art codes. The list of applications includes:

(1) statistical tabular data confidentiality; (2) support vector machines; (3) minimum convex cost flows in bipartite networks; (4) and multiperiod facility location (a mixed integer linear optimization problem). Computational results showing the efficiency of the method will be reported for instances of up to 1000 million variables and 5 million constraints.

Seminarios previos:

14/06/21Ricardo MartínezCompensation and sacrifice in the probabilistic rationing of indivisible units Ver el seminario
31/05/21Jordi CastroAn interior-point solver for large block-angular problems and applications Ver el seminario
24/05/21José Luis ZofíoIs more always better? On the relevance of decreasing returns to scale on innovation Ver el seminario
19/05/21Mesa abierta (varios autores) Datos abiertos en Ciencias de la Salud: necesidades y utilidad social

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17/05/21Alexey KapustyanGLOBAL ATTRACTORS THEORY AND ITS APPLICATION TO EVOLUTIONARY SYSTEMS WITHOUT UNIQUENESS AND IMPULSIVE SYSTEMS Ver el seminario
10/05/21Francisco Saldanha-da-GamaProject Scheduling with Flexible Resources: Is there a good optimization model? Ver el seminario
04/05/21Juan de Dios Moreno TerneroOn the axiomatic approach to sharing the revenues from broadcasting sports leagues Ver el seminario
26/04/21Cristina PoloMedición de la eficiencia de servicios públicos y la importancia del contexto no controlable. Alternativas metodológicas y aplicaciones prácticas Ver el seminario
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15/03/21Mikel SesmaDirectional monotonicity and related concepts in the context of data aggregation Ver el seminario
11/03/21Silvina Caino-LoresConvergence of High-Performance Computing and Big Data Analytics: Applications and Open Challenges Ver el seminario
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15/02/21María Ángeles García-FerreroApplications of unique continuation and Runge approximation for local and nonlocal PDEs Ver el seminario
08/02/21Magdalena KapelkoAssessing Corporate Social Responsibility Efficiency for the International Food and Beverage Manufacturing Industry Ver el seminario
01/02/21Shashiryar NasirovDecarbonization of the Chilean Power Sector: A Dynamic General Equilibrium Modeling Analysis  Ver el seminario
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21/12/20Senén Barro AmeneiroInteligencia Artificial en una sociedad de dispositivos Ver el seminario
14/12/20Judit Muñoz MatuteThe application of Discontinuous Petrov-Galerkin method for time-dependent Partial Differential Equations   Ver el seminario
07/12/20Dolores Romero MoralesExplaining Machine Learning Outcomes by Means of Mathematical Optimization Ver el seminario
30/11/20Francesco CiardielloOn Pure-Strategy Nash Equilibria in a Duopolistic Market Share Model Ver el seminario
23/11/20Carlos Hernández BarruecoImpacto económico de la Transformación Digital en las empresas Ver el seminario
16/11/20María Cumplido CabelloTeoría de trenzas: un puente entre la geometría y el álgebra Ver el seminario
09/11/20Laureano EscuderoOn the Stochastic Dominance functional-based risk averse versions in mathematical optimization under uncertainty Ver el seminario
03/11/20David RíosAdversarial Machine Learning: Perspectives from Adversarial Risk Analysis Ver el seminario
27/10/20Diego Alonso OranRegularidad de soluciones para modelos de mecánica de fluidos  Ver el seminario
19/10/20Dae-Jin LeeCiencia de datos, tecnología y deporte: retos y experiencias desde la perspectiva de la investigación matemática  Ver el seminario
13/10/20Virgilio GómezSistemas de información epidemiológicos para análisis de datos Ver el seminario
05/10/20Alberto EncisoIn Brussels and back again: some thoughts about the projects GEOFLUIDS (StG 2014) and FLUSPEC (CoG 2019)  Ver el seminario
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02/07/20Behzad HezarkhanGain-sharing in urban consolidation centers Ver el seminario
22/06/20Guillem DuránInvestigando síntesis de programas en Python Ver el seminario
15/06/20Marco LópezImpacto social de las matemáticas Ver el seminario
08/06/20Jan-J. RückmannStabilityof C-stationary Points for Mathematical Programs with Complementarity Constraints Ver el seminario
01/06/20Joscha KrauseRegularized Small Area Estimation: A Framework for Robust Estimates in the Presence of Unknown Measurement Errors Ver el seminario
25/05/20Sergio HernándezEl comportamiento inteligente como un problema de optimización resoluble. Ver el seminario
18/05/20DANIEL SANTÍNComparing the Evolution of Productivity and Performance Gaps in Education Systems through DEA: An Application to Latin American Countries Ver el seminario
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04/05/20VÍCTOR DEMIGUELOptimal Portfolio Diversification via Independent ComponentAnalysis Ver el seminario
27/04/20VÍCTOR BLANCOEl problema de Weber y problemas de cubrimiento relacionados: polielipsoides. Ver el seminario