Bourbaki

Proposition 3

Tag 035Q, permanent. Cite it as [Bourbaki, Tag 035Q].

Théories spectrales, chapter IV, § 5. Opérateurs partiels normaux et théorème spectral

Let ff be a universally measurable function defined on the spectrum of uu. The set DfD_f is a dense vector subspace of E. The mapping y↦y\mapsto evy(f)_y(f) is a normal partial operator on E whose domain is DfD_f, and which is denoted by f(u)f(u).

For every x∈Ex\in E and every y∈Dfy\in D_f, one has f∈L1f\in \mathscr{L}^1(Sp(uu),μx,y, \mu_{x,y}) and

⟨x∣f(u)y⟩=∫fμx,y(6) \langle x|f(u)y\rangle =\int f \mu_{x,y} \tag{6}

Sp(uu)

We shall prove the following more precise statement:

Bourbaki sets the proof directly after the statement, and the corpus does not separate them, so what is above is the statement and its proof together.

Cited by

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Cites

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Machine translation of the English, by gpt-5.4, gpt-5-6-mini, against glossary version 34. Not checked by a person. That model is a cut down version of the one the rest of this language was written by.