Proposition 3
Tag 096G, permanent. Cite it as [Bourbaki, Tag 096G].
Integration, chapter V, § 7. Integration with respect to an induced measure
— Let X be a locally compact subspace of T, and a complex measure on X. The following properties are equivalent: a) the canonical injection is -proper; b) for every compact subset K of T, is essentially -integrable; c) every point admits a neighborhood V such that is essentially -integrable; d) there exists a measure on T such that . If these equivalent conditions are satisfied, we have, with notations as in d),
The injection being continuous, the equivalence of the properties a), b) and c) follows from Prop. 1 of §6, and the remark that follows it, applied to the positive measure . If is induced on X by a measure on T, then (formula (6)), consequently (Prop. 1) for every compact subset K of T, so that d) implies b). Suppose that a) is satisfied, and let us show that , which will imply d). Let g be an element of ; denoting by the extension by 0 of g to T we have, by the definition of induced measure and then by Prop. 7 of §6, No. 4,
This completes the proof of the equivalence of the four properties. If and , then
because is the extension by 0 of to T. This proves the second formula of (7).
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.