Bourbaki

Proposition 4

Tag 096J, permanent. Cite it as [Bourbaki, Tag 096J].

Integration, chapter V, § 7. Integration with respect to an induced measure

— Let X and Y be two locally compact subspaces of T such that Y ⊂ X. If θ is a complex measure on T, then the measure (θ_X)_Y induced by θ_X on Y is equal to θ_Y ('transitivity of induced measures').

It suffices to observe that if g is an element of H(Y;C)\mathscr{H}(Y; \mathbf{C}), then the extension by 0 of g to T may be obtained by extending by 0 the extension by 0 of g to X, or again, making use of the identifications of the Scholium, that φY⋅θ=φY(φX⋅θ)\varphi_Y · \theta = \varphi_Y(\varphi_X · \theta) (§5, No. 4, Prop. 8).

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.