Bourbaki

Remark 4

Tag 09FF, permanent. Cite it as [Bourbaki, Tag 09FF].

Integration, VII, p. 36, § 2. Quotient of a space by a group; homogeneous spaces

Let mm be a vectorial measure on X/HX/H with values in EE, and let qq be a lower semi-continuous semi-norm on EE. For mm to be qq-majorizable (Ch. VI, §2, No. 3, Def. 3), it is necessary and sufficient that m#m^\# be so, in which case q(m#)=q(m)#q(m^\#) = q(m)^\#. This follows at once from the definitions and Cor. 3 a).

On the other hand, let μ\mu be a positive measure on X/HX/H. For mm to be scalarly of base μ\mu, it is necessary and sufficient that m#m^\# be scalarly of base μ#\mu^\#: this follows from Cor. 1.

Finally, if mm has base μ\mu, with density ff with respect to μ\mu (Ch. VI, §2, No. 4, Def. 4), then m#m^\# has base μ#\mu^\#, with density f∘πf \circ \pi: this follows from Prop. 6 c).

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.