Bourbaki

Proposition 2

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

Integration, VII, p. 28, § 2. Quotient of a space by a group; homogeneous spaces

The mapping f↦fχf \mapsto f^{\chi} of K(X)\mathscr{K}(X) into Kχ(X)\mathscr{K}^{\chi}(X) is linear, and the image of K(X)\mathscr{K}(X) (resp. K+(X)\mathscr{K}_{+}(X)) is Kχ(X)\mathscr{K}^{\chi}(X) (resp. K+χ(X)\mathscr{K}_{+}^{\chi}(X)).

Linearity is immediate. It is clear that fχ⩾0f^{\chi} \geqslant 0 for f⩾0f \geqslant 0. It then suffices to apply the following lemma:

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

Cited by

Cites

Nothing.

Transcribed from the printed volume. Not translated.