Bourbaki

Corollary 1

Tag 0630, permanent. Cite it as [Bourbaki, Tag 0630].

Algebra, chapter III, § 7. Exterior algebras

Let H,KH, K be two complementary subsets of the interval [1,n][1, n] of N\mathbf{N} and let (ih)1≤h≤p,(jk)1≤k≤n−p(i_h)_{1 \leq h \leq p}, (j_k)_{1 \leq k \leq n-p} be the sequences of elements of HH and KK respectively, arranged in increasing order; we write

xH=xi1∧xi2∧⋯∧xip,xK=xj1∧xj2∧⋯∧xjn−p; x_H = x_{i_1} \wedge x_{i_2} \wedge \cdots \wedge x_{i_p}, \quad x_K = x_{j_1} \wedge x_{j_2} \wedge \cdots \wedge x_{j_{n-p}};

then

xH∧xK=(−1)νx1∧x2∧⋯∧xn x_H \wedge x_K = (-1)^{\nu} x_1 \wedge x_2 \wedge \cdots \wedge x_n

where ν\nu is the number of ordered pairs (i,j)∈H×K(i, j) \in H \times K such that i>ji > j.

By Proposition 5 this reduces to proving

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

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Cites

Transcribed from the printed edition, 1998, Springer. Not translated.