Bourbaki

Proposition 10

Tag 098V, permanent. Cite it as [Bourbaki, Tag 098V].

Integration, chapter VI, § 1. Integration of vector-valued functions

— Let UU be a mapping of TT into F=Ls(G;H)F = \mathscr{L}_s(G; H). In each of the following three cases, UU is scalarly essentially μ\mu-integrable and ∫Udμ∈Ls(G;H)\int U d\mu \in \mathscr{L}_s(G; H):

a) HH is quasi-complete, μ\mu is bounded and, if SS is its support, UU is μ\mu-measurable and U(S)U(S) is equicontinuous.

b) HH is semi-reflexive, μ\mu is bounded and, if SS is its support, UU is scalarly μ\mu-measurable and U(S)U(S) is equicontinuous.

c) HH is semi-reflexive, GG is barreled, UU is scalarly essentially μ\mu-integrable, and, for every compact subset KK of TT, U(K)U(K) is bounded.

The fact that UU is scalarly essentially integrable is obvious in all three cases; by virtue of Prop. 9 and its corollary, it suffices in each case to verify condition a) of Prop. 9. Now, this condition follows from Prop. 8 of No. 2 in the first case, and from the Cor. of Prop. 7 of No. 2 in the other two cases.

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

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Transcribed from the printed volume. Not translated.