Proposition 6
Tag 01L4, permanent. Cite it as [Bourbaki, Tag 01L4].
Lie Groups and Lie Algebras, chapter VIII, § 1. The Lie algebra sl(2, k) and its representations
Let E be a finite dimensional -module, and . Let be the set of elements of E of weight .
(i) is a bijection from to .
(ii) is the homothety with ratio on .
If , the proposition follows from formulas (4) and (6). The general case follows from Th. 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.