Paper 4, Section I, G

Analysis II | Part IB, 2010

Let SS denote the set of continuous real-valued functions on the interval [0,1][0,1]. For f,gSf, g \in S, set

d1(f,g)=sup{f(x)g(x):x[0,1]} and d2(f,g)=01f(x)g(x)dxd_{1}(f, g)=\sup \{|f(x)-g(x)|: x \in[0,1]\} \quad \text { and } \quad d_{2}(f, g)=\int_{0}^{1}|f(x)-g(x)| d x

Show that both d1d_{1} and d2d_{2} define metrics on SS. Does the identity map on SS define a continuous map of metric spaces (S,d1)(S,d2)?\left(S, d_{1}\right) \rightarrow\left(S, d_{2}\right) ? Does the identity map define a continuous map of metric spaces (S,d2)(S,d1)\left(S, d_{2}\right) \rightarrow\left(S, d_{1}\right) ?

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