Library / Algebra / Chapter IX / § 6
Corollary 2
Tag 0DLJ, permanent. Cite it as [Bourbaki, Tag 0DLJ].
Algebra, chapter IX, § 6. Propriétés spéciales aux formes hermitiennes
*Let A \mathbf{A} A be a field and R R R a hermitian matrix of order n n n and of rank r r r over A \mathbf{A} A . Then, unless the following condition is satisfied:
(C') A \mathbf{A} A is commutative of characteristic 2, J \mathbf{J} J is the identity, R R R is alternating and non-zero,* there exists an invertible matrix P P P of order n n n over A A A such that
t P . R . P ‾ = ( α 1 0 … 0 … 0 0 α 2 … 0 … 0 ⋯ ⋯ 0 0 … α r … 0 0 0 … 0 … 0 ⋯ ⋯ 0 0 … 0 … 0 )
tP . R . \overline{P} = \begin{pmatrix}
\alpha_1 & 0 \ldots 0 \ldots 0 \\
0 & \alpha_2 \ldots 0 \ldots 0 \\
\cdots & \cdots \\
0 & 0 \ldots \alpha_r \ldots 0 \\
0 & 0 \ldots 0 \ldots 0 \\
\cdots & \cdots \\
0 & 0 \ldots 0 \ldots 0
\end{pmatrix}
tP . R . P = α 1 0 ⋯ 0 0 ⋯ 0 0 … 0 … 0 α 2 … 0 … 0 ⋯ 0 … α r … 0 0 … 0 … 0 ⋯ 0 … 0 … 0
where α ‾ i = α i ≠ 0 \overline{\alpha}_i = \alpha_i \neq 0 α i = α i = 0 for i = 1 , … , r i = 1, \ldots, r i = 1 , … , r .
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.
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Translated with machine help, not yet reviewed by a person.