Abelian subalgebras and ideals of maximal dimension in Lie algebras

En esta tesis se han estudiado subálgebras e ideales abelianos de álgebras de Lie, considerando dos invariantes, llamados alfa y beta, que representan el máximo entre la dimensión de todas las subálgebras abelianas (ideales para la beta) de un álgebra de Lie. Hemos desarrollado un estudio teórico en el capítulo dos, con algunos límites generales y propiedades. Después de eso, se han estudiado los casos de codimensión 1, 2 y 3. También hemos tratado la obtención de subálgebras abelianas y los ideales de varias familias específicas de álgebras de Lie resolubles. Después, hemos implementado un método algorítmico para calcular el valor de los invariantes alfa y beta, así como un representante de ellos. Y por último, mostramos algunas aplicaciones.In this thesis, we have studied abelian subalgebras and ideals of Lie algebras by considering two invariants, named alpha and beta, which represent the maximum among the dimension of all the abelian subalgebras (ideals for beta) of a Lie algebra. We have developed a theoretical study in Chapter two with some general bounds and properties. After that, we have studied the cases of codimension 1, 2 and 3. We have also dealt with the obtainment of abelian subalgebras and ideals in several specific families of solvable lie algebras. Then, we have implemented an algorithmic method to compute the value of alpha and beta invariants, as well as a representative for them. Finally, some applications are shown.Premio Extraordinario de Doctorado U

Symbolic and iterative computation of quasi-filiform nilpotent lie algebras of dimension nine

This paper addresses the problem of computing the family of two-filiform Lie algebra laws of dimension nine using three Lie algebra properties converted into matrix form properties: Jacobi identity, nilpotence and quasi-filiform property. The interest in this family is broad, both within the academic community and the industrial engineering community, since nilpotent Lie algebras are applied in traditional mechanical dynamic problems and current scientific disciplines. The conditions of being quasi-filiform and nilpotent are applied carefully and in several stages, and appropriate changes of the basis are achieved in an iterative and interactive process of simplification. This has been implemented by means of the development of more than thirty Maple modules. The process has led from the first family formulation, with 64 parameters and 215 constraints, to a family of 16 parameters and 17 constraints. This structure theorem permits the exhaustive classification of the quasi-filiform nilpotent Lie algebras of dimension nine with current computational methodologies. © 2015 by the authors