On a conjecture of Whittaker concerning uniformization of hyperelliptic curves

Authors:
Ernesto Girondo and Gabino González-Diez

Journal:
Trans. Amer. Math. Soc. **356** (2004), 691-702

MSC (2000):
Primary 30F10; Secondary 14H15

DOI:
https://doi.org/10.1090/S0002-9947-03-03441-X

Published electronically:
September 22, 2003

MathSciNet review:
2022716

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Abstract: This article concerns an old conjecture due to E. T. Whittaker, aiming to describe the group uniformizing an arbitrary hyperelliptic Riemann surface as an index two subgroup of the monodromy group of an explicit second order linear differential equation with singularities at the values .

Whittaker and collaborators in the thirties, and R. Rankin some twenty years later, were able to prove the conjecture for several families of hyperelliptic surfaces, characterized by the fact that they admit a large group of symmetries. However, general results of the analytic theory of moduli of Riemann surfaces, developed later, imply that Whittaker's conjecture cannot be true in its full generality.

Recently, numerical computations have shown that Whittaker's prediction is incorrect for random surfaces, and in fact it has been conjectured that it only holds for the known cases of surfaces with a large group of automorphisms.

The main goal of this paper is to prove that having many automorphisms is not a necessary condition for a surface to satisfy Whittaker's conjecture.

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Additional Information

**Ernesto Girondo**

Affiliation:
Departamento de Matemáticas, Universidad Autónoma de Madrid, Madrid 28049, Spain

Email:
ernesto.girondo@uam.es

**Gabino González-Diez**

Affiliation:
Departamento de Matemáticas, Universidad Autónoma de Madrid, Madrid 28049, Spain

Email:
gabino.gonzalez@uam.es

DOI:
https://doi.org/10.1090/S0002-9947-03-03441-X

Keywords:
Accessory parameters,
Schwarzian derivative,
uniformization of Riemann surfaces,
hyperelliptic curves

Received by editor(s):
July 23, 2002

Published electronically:
September 22, 2003

Additional Notes:
Both authors were supported in part by Grant BFM2000-0031, DGI.MCYT

Article copyright:
© Copyright 2003
American Mathematical Society