Bourbaki

Corollary 3

Tag 0CC8, permanent. Cite it as [Bourbaki, Tag 0CC8].

General Topology, chapter X, § 2. Equicontinuous sets

Let T, X be topological spaces, let Y be a uniform space and let f be a mapping of T × X into Y. Then f is continuous, provided that the following conditions are satisfied:

1) For each x∈Xx \in X, the partial mapping t→f(t,x)t \to f(t, x) is continuous.

2) As t runs through T, the partial mappings x→f(t,x)x \to f(t, x) form an equicontinuous subset of F(X;Y)\mathscr{F}(X; Y).

In particular, take T to be a subset H of F(X;Y)\mathscr{F}(X; Y) and f to be the canonical mapping (h,x)→h(x)(h, x) \to h(x) of H×XH \times X into Y; condition 1) of Corollary 3 means that H is endowed with a topology finer than that of pointwise convergence, and condition 2) means that H is equicontinuous. 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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Transcribed from the printed volume. Not translated.