Bourbaki

Lemma 10

Tag 036V, permanent. Cite it as [Bourbaki, Tag 036V].

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

We have

⟨x∣u(x)⟩⩾ϱe∥x∥2(18) \langle x|u(x)\rangle \geqslant \varrho_e\|x\|^2 \tag{18}

for every x∈Eh∩x\in E_h\cap dom(uu).

If x∈Eh∩x\in E_h\cap dom(uu), then the support of the spectral measure μx\mu_x of xx relative to uu is contained in the interval [ϱe,+∞[[\varrho_e,+\infty [ (Prop. 9, a) of IV, p. 278), hence

⟨x∣u(x)⟩=∫Rtdμx(t)⩾ϱe∥x∥2 \langle x|u(x)\rangle =\int_{\mathbf{R}}td\mu_x(t)\geqslant \varrho_e\|x\|^2

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.

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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.