Paper 1, Section II, 23G
Part II, 2011
Suppose that and are Riemann surfaces, and is a discrete subset of . For any continuous map which restricts to an analytic map of Riemann surfaces , show that is an analytic map.
Suppose that is a non-constant analytic function on a Riemann surface . Show that there is a discrete subset such that, for defines a local chart on some neighbourhood of .
Deduce that, if is a homeomorphism of Riemann surfaces and is a non-constant analytic function on for which the composite is analytic on , then is a conformal equivalence. Give an example of a pair of Riemann surfaces which are homeomorphic but not conformally equivalent.
[You may assume standard results for analytic functions on domains in the complex plane.]