Bourbaki

Proposition 1

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

General Topology, chapter III, § 3. Uniform structures on groups

The left and right translations are isomorphisms of the right uniformity onto itself.

As to the right translations, the result is clear, since the relation yx−1∈Vyx^{-1} \in V is equivalent to (ya)(xa)−1∈V(ya)(xa)^{-1} \in V [in other words, the mapping (x,y)→(xa,ya)(x, y) \to (xa, ya) leaves VdV_d fixed]. For the left translations, the result follows from (GVIII)(GV_{\text{III}}); for yx−1∈Vyx^{-1} \in V if and only if (ay)(ax)−1∈aVa−1(ay)(ax)^{-1} \in aV a^{-1}; hence x→axx \to ax is uniformly continuous on GdG_d.

Similarly, the right and left translations are isomorphisms of the left uniformity onto itself.

Every inner automorphism x→axa−1x \to axa^{-1} of GG is therefore an automorphism for the group structure of GG, for the topology of GG, and for both the uniformities of GG.

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

Cited by

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Cites

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Transcribed from the printed volume. Not translated.