Universidad de Málaga

¿Qué es un Grupo Amenable?

date
-
modality
In person
speaker
Jorge Pérez García
description

Los grupos amenables nacieron junto con la integral de Lebesgue
y desde entonces han terminado por impregnar muchas áreas de las
Matemáticas, desde la Teoría Geométrica de Grupos al Análisis Funcional o
la Teoría Ergódica.

host
José Luis Flores Dorado
activity type

Seminario de Geometría

date
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modality
In person
speaker
Vicente Muñoz
description
Título: K-contact and Sasakian manifolds of dimension 5
Conferenciante: Vicente Muñoz (Universidad de Málaga)
Resumen: Sasakian manifolds are odd-dimensional counterparts of Kahler manifolds in even dimensions, with K-contact manifolds corresponding to symplectic manifolds. It is an interesting problem to find obstructions for a closed manifold to admit such types of structures and in particular, to construct K-contact manifolds which do not admit Sasakian structures.
In the simply-connected case, the hardest dimension is 5, where Kollár has found subtle obstructions to the existence of Sasakian structures, associated to the theory of algebraic surfaces. In this talk, we develop methods to distinguish K-contact manifolds from Sasakian ones in dimension 5. In particular, we find the first example of a closed 5-manifold with first Betti number \( b_1= 0\) which is K-contact but which carries no semi-regularSasakian structure (Joint work with J.A. Rojo and A. Tralle).
Fecha: 5 de octubre de 2018, 11:30-12:30
Lugar: Seminario 1, IEMath-GR
activity type

Seminario de Ecuaciones Diferenciales

date
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modality
In person
speaker
Manuel J. Castro Díaz
description

Conferenciante: Manuel J. Castro Díaz (Universidad de Málaga)
Título: "Approximate Osher-Solomon Schemes for hyperbolic systems"
Fecha y hora: Jueves 20 de abril de 2017, 13:10
Lugar de encuentro: Seminario de la primera planta, IEMath-GR
Resumen:
This talk is concerned with a new kind of Riemann solvers for hyperbolic systems, which can be applied both in the conservative and nonconservative cases. In particular, the proposed schemes constitute a simple version of the classical Osher-Solomon Riemann solver (see [Osher-Solomon 1982]), and extend in some sense the schemes proposed in [Dumbser-Toro 2011]. The viscosity matrix of the numerical flux is constructed as a linear combination of functional evaluations of the Jacobian of the flux at several quadrature points. Some families of functions have been proposed to this end: Chebyshev polynomials and rational-type functions (see Castro-Gallardo-Marquina 2014). The schemes have been tested with different initial value Riemann problems for ideal gas dynamics, magnetohydrodynamics and multilayer shallow water equations. The numerical tests indicate that the proposed schemes are robust, stable and accurate with a satisfactory time step restriction, and provide an efficient alternative for approximating time-dependent solutions in which the spectral decomposition is computationally expensive.

activity type