Paper 2, Section I, 2F2 F

Analysis and Topology
Part IB, 2021

Let K:[0,1]×[0,1]RK:[0,1] \times[0,1] \rightarrow \mathbb{R} be a continuous function and let C([0,1])C([0,1]) denote the set of continuous real-valued functions on [0,1][0,1]. Given fC([0,1])f \in C([0,1]), define the function TfT f by the expression

Tf(x)=01K(x,y)f(y)dyT f(x)=\int_{0}^{1} K(x, y) f(y) d y

(a) Prove that TT is a continuous map C([0,1])C([0,1])C([0,1]) \rightarrow C([0,1]) with the uniform metric on C([0,1])C([0,1]).

(b) Let d1d_{1} be the metric on C([0,1])C([0,1]) given by

d1(f,g)=01f(x)g(x)dxd_{1}(f, g)=\int_{0}^{1}|f(x)-g(x)| d x

Is TT continuous with respect to d1?d_{1} ?