Bourbaki

Proposition 13

Tag 0AFF, permanent. Cite it as [Bourbaki, Tag 0AFF].

Lie Groups and Lie Algebras, chapter III, § 6. Real and complex Lie groups

Let GG be a connected Lie group and φ\varphi an analytic linear representation of GG on a complete normable space EE. Let E1,E2E_1, E_2 be two closed vector subspaces of EE such that E2⊂E1E_2 \subset E_1. The following conditions are equivalent:

(i) φ(g)x≡x(modE2)\varphi(g)x \equiv x \pmod{E_2} for all g∈Gg \in G and all x∈E1x \in E_1; (ii) L(φ)(L(G))L(\varphi)(L(G)) maps E1E_1 into E2E_2.

φ(g)x≡x(mod E2)for all g∈G and all x∈E1⇔φ(exp⁡a)x≡x(mod E2)for all a∈L(G) and all x∈E1⇔(exp⁡L(φ)a)x≡x(mod E2)for all a∈L(G) and all x∈E1. \begin{align*} &\varphi(g)x \equiv x \quad (\text{mod } E_2) \quad \text{for all } g \in G \text{ and all } x \in E_1 \\ \Leftrightarrow &\varphi(\exp a)x \equiv x \quad (\text{mod } E_2) \quad \text{for all } a \in L(G) \text{ and all } x \in E_1 \\ \Leftrightarrow &(\exp L(\varphi)a)x \equiv x \quad (\text{mod } E_2) \quad \text{for all } a \in L(G) \text{ and all } x \in E_1. \end{align*}

On the other hand, if u∈L(E)u \in \mathscr{L}(E), then

exp⁡(λu)x≡x(mod E2)for all λ∈K and all x∈E1⇔u(E1)⊂E2 \begin{align*} &\exp(\lambda u)x \equiv x \quad (\text{mod } E_2) \quad \text{for all } \lambda \in K \text{ and all } x \in E_1 \\ \Leftrightarrow &u(E_1) \subset E_2 \end{align*}

whence the proposition.

Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.

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Cites

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Transcribed from the printed volume. Not translated.