En esta charla se discute el clásico Teorema de Rigidez de Ilyashenko para foliaciones polinomiales y las dificultades que presenta su generalización a foliaciones en el plano proyectivo. En general estas foliaciones no son topológicamente rígidas, pero es plausible que sí lo sean genéricamente. Se muestra que la foliación genérica de grado es diferenciablemente rígida. El ingrediente fundamental para obtener este resultado es el estudio de la invariancia diferenciable de los índices de Camacho-Sad y Baum-Bott.

El presente artículo es una exposición concisa y autocontenida sobre los tres grandes problemas de la antigüedad y sus soluciones. La intención es introducir el concepto abstracto de cuerpo y algunas estructuras matemáticas subyacentes.

El artículo no presenta resumen

In this article we show several properties about multiply Hölder functions. We study the Hölder class of a composition of multiply Hölder functions and prove that a map and its inverse belong — under certain hypotheses — to the same Hölder class. We also prove some extension properties of multiply Hölder functions; for example, we show that a multiply Hölder functions always extends, in the same Hölder class, to “exceptional” sets that are codimension one manifolds.

We are interested in characterizing the holonomy maps associated to integral curves of nondegenerate singularities of holomorphic vector fields. Such a description is well-known in dimension 2 where is a key ingredient in the study of reduced singularities. Themost intricate case in the 2 dimensional setting corresponds to (Siegel) saddle singularities. This work treats the analogous problem for saddles in higher dimension. We show that any germ of holomorphic biholomorphism, in any dimension, can be obtained as the holonomy map associated to an integral curve of a saddle singularity. A natural question is whether we can prescribe the linear part of the saddle germ of vector field provided the holonomy map. The answer to this question is known to be positive in dimension 2.We see that this is not the case in higher dimension. In spite of this, we provide a positive result under a natural...