Bourbaki

Corollary

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

Lie Groups and Lie Algebras, chapter V, § 2. Reflections

If V is finite dimensional, every reflection is of determinant −1.

Let s be a reflection in V. Prop. 2, (i) shows that there exists a basis (e1,…,en)(e_1, \ldots, e_n) of V such that s(e1)=e1,…,s(en−1)=en−1s(e_1) = e_1, \ldots, s(e_{n-1}) = e_{n-1} and s(en)=−ens(e_n) = -e_n, hence det⁡(s)=−1\det(s) = -1.

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

Cited by

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Cites

Transcribed from the printed volume. Not translated.