Bourbaki

Proposition 2

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

General Topology, chapter II, § 4. Relations between uniform spaces and compact spaces

Let f:X→Yf : X \to Y be a uniformly continuous mapping. If AA is any precompact subset of XX, then f(A)f(A) is a precompact subset of YY.

For if i:X→X^i : X \to \hat{X} and j:Y→Y^j : Y \to \hat{Y} are the canonical mappings, we have j(f(A))=f^(i(A))j(f(A)) = \hat{f}(i(A)) (§ 3, no. 7, Proposition 15) and hence j(f(A))j(f(A)) is relatively compact in Y^\hat{Y} (Chapter I, § 9, no. 4, Theorem 2, Corollary 1).

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

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