Bourbaki

Corollary 3

Tag 0CB7, permanent. Cite it as [Bourbaki, Tag 0CB7].

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

Let HH be a subset of F(X;Y)\mathscr{F}(X; Y) such that, for each

x∉B=⋃A∈GA, x \notin B = \bigcup_{A \in \mathscr{G}} A,
the closure of H(x)H(x) in YY is a complete subspace of YY. Then the closure H‾\overline{H} of HH in FG(X;Y)\mathscr{F}_{\mathscr{G}}(X; Y) is a complete subspace.

Let Φ\Phi be a Cauchy filter on H‾\overline{H}, and define a mapping v:X→Yv : X \to Y as follows. If x∈Bx \in B, Φ(x)\Phi(x) is a Cauchy filter on H(x)‾\overline{H(x)} (no. 2, Remark 6), hence by hypothesis it has at least one limit point; take v(x)v(x) to be one of these limits. If x∉Bx \notin B, take v(x)v(x) to be any point of YY. With this definition of vv, it is clear that Φ\Phi converges pointwise to vv in BB, and vv is therefore a limit of Φ\Phi in FG(X;Y)\mathscr{F}_{\mathscr{G}}(X; Y) by Proposition 5.

In particular, if YY is complete, the hypothesis of Corollary 3 of Proposition 5 is satisfied for every H⊂F(X;Y)H \subset \mathscr{F}(X; Y); hence:

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

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Cites

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