Paper 2, Section II, F

Riemann Surfaces
Part II, 2021

Let DCD \subseteq \mathbb{C} be a domain, let (f,U)(f, U) be a function element in DD, and let α:[0,1]D\alpha:[0,1] \rightarrow D be a path with α(0)U\alpha(0) \in U. Define what it means for a function element (g,V)(g, V) to be an analytic continuation of (f,U)(f, U) along α\alpha.

Suppose that β:[0,1]D\beta:[0,1] \rightarrow D is a path homotopic to α\alpha and that (h,V)(h, V) is an analytic continuation of (f,U)(f, U) along β\beta. Suppose, furthermore, that (f,U)(f, U) can be analytically continued along any path in DD. Stating carefully any theorems that you use, prove that g(α(1))=h(β(1))g(\alpha(1))=h(\beta(1)).

Give an example of a function element (f,U)(f, U) that can be analytically continued to every point of C\mathbb{C}_{*} and a pair of homotopic paths α,β\alpha, \beta in C\mathbb{C}_{*} starting in UU such that the analytic continuations of (f,U)(f, U) along α\alpha and β\beta take different values at α(1)=β(1)\alpha(1)=\beta(1).