Bourbaki

Corollary 2

Tag 01GF, permanent. Cite it as [Bourbaki, Tag 01GF].

Lie Groups and Lie Algebras, chapter IX, § 7. Irreducible representations of connected compact Lie groups

For all λ∈X++\lambda \in X_{++} and every regular element tt of T,

χλ(t)=∑∑wεw(wε)(λw()wtρ()wtρ()wt)(5) \chi_{\lambda}(t) =\sum\sum^w\varepsilon_w(w\varepsilon )(\lambda w()wt\rho ()wt\rho ()wt) \tag{5}

where the two sums are over the elements ww of W.

Indeed, J(ρ)(t)J(\rho )(t) is non-zero, since tt is regular (formula (4)).

If φ\varphi is a central function on G, the restriction of φ\varphi to T is invariant under W, so J(ρ).φ∣TJ(\rho ).\varphi |T is anti-invariant under W. Further, by Spectral Theories and Th. 1, the family (χλ)λ∈X++(\chi_{\lambda})_{\lambda\in X_{++}} is an algebraic basis of the space of central representative functions on G and an orthonormal basis of the space ZL2(G)^2(G) of classes of square-integrable central functions on G.

Thus, from Prop. 3 and Th. 2 we deduce:

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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Transcribed from the printed volume. Not translated.