Theorems · Theorem · linear algebra

MultilinearMap.map_sum

∀ {R : Type uR} {ι : Type uι} {M₁ : ι → Type v₁} {M₂ : Type v₂} [inst : Semiring R]
  [inst_1 : (i : ι) → AddCommMonoid (M₁ i)] [inst_2 : AddCommMonoid M₂] [inst_3 : (i : ι) → Module R (M₁ i)]
  [inst_4 : Module R M₂] (f : MultilinearMap R M₁ M₂) {α : ι → Type u_1} (g : (i : ι) → α i → M₁ i)
  [inst_5 : DecidableEq ι] [inst_6 : Fintype ι] [inst_7 : (i : ι) → Fintype (α i)],
  (f fun i => ∑ j, g i j) = ∑ r, f fun i => g i (r i)

If f is multilinear, then f (Σ_{j₁} g₁ j₁, ..., Σ_{jₙ} gₙ jₙ) is the sum of f (g₁ (r 1), ..., gₙ (r n)) where r ranges over all functions r. This follows from multilinearity by expanding successively with respect to each coordinate.

Defined in

Mathlib.LinearAlgebra.Multilinear.Basic

Cited by

2 results in Mathlib

Foundations

Depth 74 from the axioms · uses propext, Classical.choice, Quot.sound

Assumes

SemiringAddCommMonoidAddCommMonoidModuleModuleDecidableEqFintypeFintype