Bourbaki

Definition 3

Tag 02I1, permanent. Cite it as [Bourbaki, Tag 02I1].

Théories spectrales, chapter II, § 1. Transformation de Fourier

Let μ∈M1(G)\mu\in \mathscr{M}^1(G) be a bounded complex measure on G. The Fourier transform of μ\mu is called the function FG(μ)\mathscr{F}_G(\mu) on G^\widehat{G} defined by

FG(μ)(x^)=∫G⟨x^,x⟩‾dμ(x)(5) \mathscr{F}_G(\mu)(\widehat{x}) =\int_G\overline{\langle\widehat{x}, x\rangle}d\mu(x) \tag{5}

The Fourier cotransform of μ\mu is called the function F‾G(μ)\overline{\mathscr{F}}_G(\mu) on G^\widehat{G} defined by

F‾G(μ)(x^)=∫G⟨x^,x⟩dμ(x)(6) \overline{\mathscr{F}}_G(\mu)(\widehat{x}) =\int_G\langle \widehat{x}, x\rangle d\mu(x) \tag{6}

When there is no ambiguity concerning the group G considered, one shall also write F(μ)\mathscr{F}(\mu) and F‾(μ)\overline{\mathscr{F}}(\mu). One also sometimes denotes μ^=FG(μ)\widehat{\mu}=\mathscr{F}_G(\mu).

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

Nothing.

Cites

Nothing.

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.