4.II.23F
Part II, 2007
Let be a Riemann surface, a topological surface, and a continuous map. Suppose that every point admits a neighbourhood such that maps homeomorphically onto its image. Prove that has a complex structure such that is a holomorphic map.
A holomorphic map between Riemann surfaces is called a covering map if every has a neighbourhood with a disjoint union of open sets in , so that is biholomorphic for each . Suppose that a Riemann surface admits a holomorphic covering map from the unit . Prove that any holomorphic map is constant.
[You may assume any form of the monodromy theorem and basic results about the lifts of paths, provided that these are accurately stated.]