Paper 2, Section II, F

Riemann Surfaces
Part II, 2015

Let GG be a domain in C\mathbb{C}. Define the germ of a function element (f,D)(f, D) at zDz \in D. Let G\mathcal{G} be the set of all germs of function elements in GG. Define the topology on G\mathcal{G}. Show it is a topology, and that it is Hausdorff. Define the complex structure on G\mathcal{G}, and show that there is a natural projection map π:GG\pi: \mathcal{G} \rightarrow G which is an analytic covering map on each connected component of G\mathcal{G}.

Given a complete analytic function F\mathcal{F} on GG, describe how it determines a connected component GF\mathcal{G}_{\mathcal{F}} of G\mathcal{G}. [You may assume that a function element (g,E)(g, E) is an analytic continuation of a function element (f,D)(f, D) along a path γ:[0,1]G\gamma:[0,1] \rightarrow G if and only if there is a lift of γ\gamma to G\mathcal{G} starting at the germ of (f,D)(f, D) at γ(0)\gamma(0) and ending at the germ of (g,E)(g, E) at γ(1)\gamma(1).]

In each of the following cases, give an example of a domain GG in C\mathbb{C} and a complete analytic function F\mathcal{F} such that:

(i) π:GFG\pi: \mathcal{G}_{\mathcal{F}} \rightarrow G is regular but not bijective;

(ii) π:GFG\pi: \mathcal{G}_{\mathcal{F}} \rightarrow G is surjective but not regular.