Bourbaki

Corollary 1

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

General Topology, chapter X, § 2. Equicontinuous sets

Let XX be a topological (resp. uniform) space, let YY be a Hausdorff uniform space and let HH be an equicontinuous (resp. uniformly equicontinuous) subset of C(X;Y)C(X; Y). Suppose that H(x)H(x) is relatively compact in YY for each x∈Xx \in X. Then HH is relatively compact in C(X;Y)C(X; Y) with respect to the topology of compact (resp. precompact) convergence.

Let H‾\overline{H} be the closure of HH in Fs(X;Y)\mathscr{F}_s(X; Y). H‾\overline{H} is equicontinuous (resp. uniformly equicontinuous) (no. 3, Proposition 6). Moreover, we have H‾(x)⊂H(x)‾\overline{H}(x) \subset \overline{H(x)} (§ 1, no. 2, Remark 6) and therefore H‾(x)\overline{H}(x) is also relatively compact; hence Theorem 2 shows that H‾\overline{H} is precompact with respect to S\mathscr{S}-convergence, where S\mathscr{S} denotes the set of all compact (resp. precompact) subsets of XX. Moreover, since H(x)‾\overline{H(x)} is compact, and therefore complete, H‾\overline{H} is complete with respect to the uniformity of pointwise convergence (Chapter II, § 3, no. 5, Proposition 10 and no. 4, Proposition 8) and therefore also with respect to the uniformity of S\mathscr{S}-convergence (§ 1, no. 5, Proposition 5, Corollary 2); H‾\overline{H} is therefore compact, since it is precompact, complete and Hausdorff (§ 1, no. 2, Proposition 1).

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

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