We study groups of germs of complex diffeomorphisms having a property called irreducibility. The notion is motivated by the similar property of the fundamental group of the complement of an irreducible hypersurface in the complex projective space. Natural examples of such groups of germ maps are given by holonomy groups and monodromy groups of integrable systems (foliations) under certain conditions. We prove some finiteness results for these groups extending previous results in [3]. Applications are given to the framework of germs of holomorphic foliations. We prove the existence of first integrals under certain irreducibility or more general conditions on the tangent cone of the foliation after a punctual blow-up.2000 Mathematics Subject Classification. Primary 37F75, 57R30; Secondary 32M25, 32S65.

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O artigo aborda um modelo específico de Geometria Não-Euclidiana, cujo disco aberto unitário centrado na origem do plano cartesiano é dotado de uma métrica de Randers, que modela o Problema da navegação de Zermelo. Com isso, é gerada a "Geometria de Funk sobre o disco unitário", para qual a distância não é simétrica. Nesse sentido, o estudo apresenta as expressões para distância de ponto a ponto - de ponto a uma linha reta, e de uma linha reta a um ponto; e caracteriza as circunferências nesse tipo de geometria. Exemplos explícitos são incluídos.

We study second order linear differential equations with analytic coefficients. One important case is when the equation admits a so called regular singular point. In this case we address some untouched and some new aspects of Frobenius methods. For instance, we address the problem of finding formal solutions and studying their convergence. A characterization of regular singularities is given in terms of the space of solutions. An analytic-geometric classification of such linear polynomial homogeneous ODEs is obtained by the use of techniques from geometric theory of foliations means. This is done by associating to such an ODE a rational Riccati differential equation and therefore a global holonomy group. This group is a computable group of Moebius maps. These techniques apply to classical equations as Bessel and Legendre equations. We also address the problem of deciding which such polynomial equations admit a Liouvillian solution. A normal form for such a solution is then obtained. Our results are concrete and (computationally) constructive and are aimed to shed a new light in this important subject.

En este artículo estamos interesados en la estabilidad de las soluciones de una ecuación de onda con una condición de frontera viscoelástica y un término fuente, usaremos el método potencial, la técnica de multiplicadores y el teorema de unicidad para una ecuación de onda con coeficientes variables.