Geometry of transcendental singularities of complex analytic functions and vector fields

TL;DR

This paper explores the geometric structure of singularities in complex analytic functions and vector fields, extending classical theories and providing new characterizations and applications related to univalence, trajectories, and special functions.

Contribution

It offers a complete classification of singularities of inverse functions of automorphic complex functions and relates these to vector field properties and geometrical structures.

Findings

Characterization of algebraic, logarithmic, and zero-residue singularities.

Descriptions of maximal univalence regions for complex trajectories.

Analysis of singularities related to the Riemann ξ function.

Abstract

On Riemann surfaces $M$, there exists a canonical correspondence between a possibly multivalued function $\Psi_X$ whose differential is single valued ($i.e.$ an additively automorphic singular complex analytic function) and a vector field $X$. From the point of view of vector fields, the singularities that we consider are zeros, poles, isolated essential singularities and accumulation points of the above. The theory of singularities of the inverse function $\Psi_X^{-1}$ is extended from meromorphic functions to additively automorphic singular complex analytic functions. The main contribution is a complete characterization of when a singularity of $\Psi_X^{-1}$ is either algebraic, logarithmic or arises from a zero with nonzero residue of $X$. Relationships between analytical properties of $\Psi_X$, singularities of $\Psi_X^{-1}$ and singularities of $X$ are presented. Families and sporadic examples showing the geometrical richness of vector fields on the neighbourhoods of the singularities of $\Psi_X^{-1}$ are studied. As applications we have; a description of the maximal univalence regions for complex trajectory solutions of a vector field $X$, a geometric characterization of the incomplete real trajectories of a vector field $X$, and a description of the singularities of the vector field associated to the Riemann $\xi$ function.