Geometry of transcendental singularities of complex analytic functions and vector fields

Abstract

We study transcendental meromorphic functions with essential singularities on Riemann surfaces. Every function Ψ X has associated a complex vector field X. In the converse direction, vector fields X provide single valued or multivalued functions Ψ X . Our goal is to understand the relationship between the analytical properties of Ψ X , the singularities of its inverse Ψ −1 X and the geometric behavior of X. As first result, by examining the containment properties of the neighborhoods of the singularities of Ψ −1 X , we characterize when a singularity of Ψ −1 X over a singular value a, is either algebraic, logarithmic or non logarithmic. Secondly, to make precise the cooperative aspects between analysis and geometry, we present the systematic study of two holomorphic families of transcendental functions with an essential singularity at infinity, as well as some sporadic examples. As third stage, we study the incompleteness of the trajectories of the associated vector field X with essential singularities on a Riemann surface Mg of genus g. As an application, we provide conditions under which there exists an infinite number of (real) incomplete trajectories of X localized at the essential singularities. Furthermore, removing the incomplete trajectories decomposes the Riemann surface into real flow invariant canonical pieces. ContentsX 4. Holomorphic families and sporadic examples 4.1. Exponential families 4.2. Families of periodic vector fields 4.3. Sporadic examples 5. Incomplete trajectories 5.1. Existence of incomplete trajectories