Bourbaki

Proposition 10

Tag 0BE7, permanent. Cite it as [Bourbaki, Tag 0BE7].

General Topology, chapter II, § 2. Uniformly continuous functions

Let II be a directed set, let (Xα,fαβ)(X_\alpha, f_{\alpha\beta}) be an inverse system of uniform spaces indexed by II, and let JJ be a cofinal subset of II. For each α∈I\alpha \in I let fαf_\alpha be the canonical mapping of X=lim←⁡XαX = \varprojlim X_\alpha into XαX_\alpha, and let gαg_\alpha denote fα×fαf_\alpha \times f_\alpha. Then the family of sets g‾α−1(Vα)\overline{g}_\alpha^{-1}(V_\alpha), where α\alpha runs through JJ and where, for each α∈J\alpha \in J, VαV_\alpha runs through a fundamental system of entourages of XαX_\alpha, is a fundamental system of entourages of XX.

We leave the proof to the reader; it is a straightforward adaptation of the proof of Proposition 9 of Chapter I, § 4, no. 4.

Finally, the topology on X=lim←⁡XαX = \varprojlim X_\alpha induced by the inverse limit of the uniformities of the XαX_\alpha is the inverse limit of the topologies of the XαX_\alpha.

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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