Paper 3, Section II, H

Linear Analysis
Part II, 2009

(a) State the Arzela-Ascoli theorem, explaining the meaning of all concepts involved.

(b) Prove the Arzela-Ascoli theorem.

(c) Let KK be a compact topological space. Let (fn)nN\left(f_{n}\right)_{n \in \mathbb{N}} be a sequence in the Banach space C(K)C(K) of real-valued continuous functions over KK equipped with the supremum norm \|\cdot\|. Assume that for every xKx \in K, the sequence fn(x)f_{n}(x) is monotone increasing and that fn(x)f(x)f_{n}(x) \rightarrow f(x) for some fC(K)f \in C(K). Show that fnf0\left\|f_{n}-f\right\| \rightarrow 0 as nn \rightarrow \infty.