Bourbaki

Lemma 1

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

General Topology, chapter III, § 7. Inverse limits of topological groups and rings

Under the hypotheses of Proposition 2, if EE is any closed subset of GG we have E=⋂αEHαE = \bigcap_\alpha E H_\alpha.

For EE is the intersection of the sets EVEV where VV runs through the neighbourhood filter of ee [§\S 3, no. 1, formula (1)], and every neighbourhood of ee contains an HαH_\alpha; whence the result, since E⊂EHαE \subset EH_\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

Transcribed from the printed volume. Not translated.