2.I.4E2 . \mathrm{I} . 4 \mathrm{E} \quad

Further Analysis | Part IB, 2004

Let τ\tau be the topology on N\mathbb{N} consisting of the empty set and all sets XNX \subset \mathbb{N} such that N\X\mathbb{N} \backslash X is finite. Let σ\sigma be the usual topology on R\mathbb{R}, and let ρ\rho be the topology on R\mathbb{R} consisting of the empty set and all sets of the form (x,)(x, \infty) for some real xx.

(i) Prove that all continuous functions f:(N,τ)(R,σ)f:(\mathbb{N}, \tau) \rightarrow(\mathbb{R}, \sigma) are constant.

(ii) Give an example with proof of a non-constant function f:(N,τ)(R,ρ)f:(\mathbb{N}, \tau) \rightarrow(\mathbb{R}, \rho) that is continuous.

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