Bourbaki

Corollary

Tag 02B3, permanent. Cite it as [Bourbaki, Tag 02B3].

Théories spectrales, chapter I, § 4. Calcul fonctionnel holomorphe

Let A be a commutative Banach algebra. Let F1F_1 and F2F_2 be two disjoint subsets of X(A)\mathsf{X}(A), closed for the Jacobson topology. Assume that F2F_2 is weakly compact. Then there exists u∈Au\in A such that G(u)=1\mathscr{G}(u) = 1 on F2F_2 and G(u)=0\mathscr{G}(u) = 0 on F1F_1.

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-5-6-mini, gpt-5-mini, gpt-5.4, 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.