Bourbaki

Proposition 7

Tag 0CBB, permanent. Cite it as [Bourbaki, Tag 0CBB].

General Topology, chapter X, § 1. The uniformity of $\mathscr{G}$-convergence

Let X be a topological space, let S\mathfrak{S} be a set of subsets of X and let Y be a uniform space. If Y is Hausdorff and if the union B of the sets of S\mathfrak{S} is dense in X, then CS(X;Y)C_{\mathfrak{S}}(X; Y) is Hausdorff.

For if (u,v)(u, v) belongs to all the sets W(A,V)W(A, V), where A∈SA \in \mathfrak{S} and V is an entourage of Y, the hypothesis that Y is Hausdorff tells us that u(x)=v(x)u(x) = v(x) for all x∈Bx \in B; if uu and vv are continuous, then u=vu = v by the principle of extension of identities (Chapter I, § 8, no. 1, Proposition 2, Corollary 1).

In particular, on C(X;Y)C(X; Y), the topology of pointwise convergence in a dense subset of X is Hausdorff.

Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.

Cited by

Nothing.

Cites

Transcribed from the printed volume. Not translated.