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Mathlib.LinearAlgebra.Multilinear.Basis

Multilinear maps in relation to bases. #

This file proves lemmas about the action of multilinear maps on basis vectors.

theorem Basis.ext_multilinear {ι : Type u_1} {R : Type u_2} [CommSemiring R] {M : ιType u_3} [(i : ι) → AddCommMonoid (M i)] [(i : ι) → Module R (M i)] {N : Type u_4} [AddCommMonoid N] [Module R N] [Finite ι] {f g : MultilinearMap R M N} {ιM : ιType u_5} (e : (i : ι) → Basis (ιM i) R (M i)) (h : ∀ (v : (i : ι) → ιM i), (f fun (i : ι) => (e i) (v i)) = g fun (i : ι) => (e i) (v i)) :
f = g

Two multilinear maps indexed by a Fintype are equal if they are equal when all arguments are basis vectors.

@[deprecated Basis.ext_multilinear (since := "2025-05-12")]
theorem Basis.ext_multilinear_fin {ι : Type u_1} {R : Type u_2} [CommSemiring R] {M : ιType u_3} [(i : ι) → AddCommMonoid (M i)] [(i : ι) → Module R (M i)] {N : Type u_4} [AddCommMonoid N] [Module R N] [Finite ι] {f g : MultilinearMap R M N} {ιM : ιType u_5} (e : (i : ι) → Basis (ιM i) R (M i)) (h : ∀ (v : (i : ι) → ιM i), (f fun (i : ι) => (e i) (v i)) = g fun (i : ι) => (e i) (v i)) :
f = g

Alias of Basis.ext_multilinear.


Two multilinear maps indexed by a Fintype are equal if they are equal when all arguments are basis vectors.