Library / Algebra / Chapter IX / § 1
Definition 12
Tag 0DJL, permanent. Cite it as [Bourbaki, Tag 0DJL].
Algebra, chapter IX, § 1. Formes sesquilinéaires
Given two A-modules E, F and a form Φ \Phi Φ sesquilinear for J on E × F E \times F E × F , the form Φ ( m ) \Phi_{(m)} Φ ( m ) sesquilinear for J on ( ∧ m E ) × ( ∧ m F ) (\wedge^m E) \times (\wedge^m F) ( ∧ m E ) × ( ∧ m F ) characterized by (37) is called the extension of Φ \Phi Φ to the m-th exterior powers.
The notations being those of Def. 12, let us study the mappings associated with Φ ( m ) \Phi_{(m)} Φ ( m ) . From formula (24) (No. 6) and (37) we obtain the relations
Φ ( m ) ( x 1 ∧ … ∧ x m , y 1 ∧ … ∧ y m ) = det ( ⟨ x i , d Φ ( y k ) ⟩ ) = det ( ⟨ y i , s Φ ( x k ) ⟩ j ) .
\Phi_{(m)}(x_1 \wedge \ldots \wedge x_m, y_1 \wedge \ldots \wedge y_m) = \det(\langle x_i, d_\Phi(y_k) \rangle)
= \det(\langle y_i, s_\Phi(x_k) \rangle^j).
Φ ( m ) ( x 1 ∧ … ∧ x m , y 1 ∧ … ∧ y m ) = det (⟨ x i , d Φ ( y k )⟩) = det (⟨ y i , s Φ ( x k ) ⟩ j ) .
We therefore have
s Φ ( m ) = k s ∘ ( ∧ m s Φ ) , d Φ m = k d ∘ ( ∧ m d Φ ) ,
s_{\Phi(m)} = k_s \circ (\wedge^m s_\Phi), \quad d_{\Phi m} = k_d \circ (\wedge^m d_\Phi),
s Φ ( m ) = k s ∘ ( ∧ m s Φ ) , d Φ m = k d ∘ ( ∧ m d Φ ) ,
where k s k_s k s (resp. k d k_d k d ) denotes the canonical mapping of ∧ m F ∗ \wedge^m F^* ∧ m F ∗ into ( ∧ m F ) ∗ (\wedge^m F)^* ( ∧ m F ) ∗ (resp. of ∧ m E ∗ \wedge^m E^* ∧ m E ∗ into ( ∧ m E ) ∗ (\wedge^m E)^* ( ∧ m E ) ∗ ) (cf. Chap. III, § 8, No. 2).
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.
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