Theorem: TensorProduct.gradedComm_of_tmul_of
File: Mathlib/LinearAlgebra/TensorProduct/Graded/External.lean

Proof steps:
state_before: R : Type u_1
ι : Type u_2
A : Type u_3
B : Type u_4
inst✝¹¹ : CommSemiring ι
inst✝¹⁰ : Module ι (Additive ℤˣ)
inst✝⁹ : DecidableEq ι
𝒜 : ι → Type u_5
ℬ : ι → Type u_6
inst✝⁸ : CommRing R
inst✝⁷ : (i : ι) → AddCommGroup (𝒜 i)
inst✝⁶ : (i : ι) → AddCommGroup (ℬ i)
inst✝⁵ : (i : ι) → Module R (𝒜 i)
inst✝⁴ : (i : ι) → Module R (ℬ i)
inst✝³ : DirectSum.GRing 𝒜
inst✝² : DirectSum.GRing ℬ
inst✝¹ : DirectSum.GAlgebra R 𝒜
inst✝ : DirectSum.GAlgebra R ℬ
i j : ι
a : 𝒜 i
b : ℬ j
⊢ (gradedComm R 𝒜 ℬ) ((lof R ι 𝒜 i) a ⊗ₜ[R] (lof R ι ℬ j) b) = (-1) ^ (j * i) • (lof R ι ℬ j) b ⊗ₜ[R] (lof R ι 𝒜 i) a
state_after: R : Type u_1
ι : Type u_2
A : Type u_3
B : Type u_4
inst✝¹¹ : CommSemiring ι
inst✝¹⁰ : Module ι (Additive ℤˣ)
inst✝⁹ : DecidableEq ι
𝒜 : ι → Type u_5
ℬ : ι → Type u_6
inst✝⁸ : CommRing R
inst✝⁷ : (i : ι) → AddCommGroup (𝒜 i)
inst✝⁶ : (i : ι) → AddCommGroup (ℬ i)
inst✝⁵ : (i : ι) → Module R (𝒜 i)
inst✝⁴ : (i : ι) → Module R (ℬ i)
inst✝³ : DirectSum.GRing 𝒜
inst✝² : DirectSum.GRing ℬ
inst✝¹ : DirectSum.GAlgebra R 𝒜
inst✝ : DirectSum.GAlgebra R ℬ
i j : ι
a : 𝒜 i
b : ℬ j
⊢ (((TensorProduct.directSum R R 𝒜 ℬ).trans
            (LinearEquiv.ofLinear (gradedCommAux R 𝒜 ℬ) (gradedCommAux R ℬ 𝒜) ⋯ ⋯)).trans
        (TensorProduct.directSum R R ℬ 𝒜).symm)
      ((lof R ι 𝒜 i) a ⊗ₜ[R] (lof R ι ℬ j) b) =
    (-1) ^ (j * i) • (lof R ι ℬ j) b ⊗ₜ[R] (lof R ι 𝒜 i) a
tactic: rw [gradedComm]
state_before: R : Type u_1
ι : Type u_2
A : Type u_3
B : Type u_4
inst✝¹¹ : CommSemiring ι
inst✝¹⁰ : Module ι (Additive ℤˣ)
inst✝⁹ : DecidableEq ι
𝒜 : ι → Type u_5
ℬ : ι → Type u_6
inst✝⁸ : CommRing R
inst✝⁷ : (i : ι) → AddCommGroup (𝒜 i)
inst✝⁶ : (i : ι) → AddCommGroup (ℬ i)
inst✝⁵ : (i : ι) → Module R (𝒜 i)
inst✝⁴ : (i : ι) → Module R (ℬ i)
inst✝³ : DirectSum.GRing 𝒜
inst✝² : DirectSum.GRing ℬ
inst✝¹ : DirectSum.GAlgebra R 𝒜
inst✝ : DirectSum.GAlgebra R ℬ
i j : ι
a : 𝒜 i
b : ℬ j
⊢ (((TensorProduct.directSum R R 𝒜 ℬ).trans
            (LinearEquiv.ofLinear (gradedCommAux R 𝒜 ℬ) (gradedCommAux R ℬ 𝒜) ⋯ ⋯)).trans
        (TensorProduct.directSum R R ℬ 𝒜).symm)
      ((lof R ι 𝒜 i) a ⊗ₜ[R] (lof R ι ℬ j) b) =
    (-1) ^ (j * i) • (lof R ι ℬ j) b ⊗ₜ[R] (lof R ι 𝒜 i) a
state_after: R : Type u_1
ι : Type u_2
A : Type u_3
B : Type u_4
inst✝¹¹ : CommSemiring ι
inst✝¹⁰ : Module ι (Additive ℤˣ)
inst✝⁹ : DecidableEq ι
𝒜 : ι → Type u_5
ℬ : ι → Type u_6
inst✝⁸ : CommRing R
inst✝⁷ : (i : ι) → AddCommGroup (𝒜 i)
inst✝⁶ : (i : ι) → AddCommGroup (ℬ i)
inst✝⁵ : (i : ι) → Module R (𝒜 i)
inst✝⁴ : (i : ι) → Module R (ℬ i)
inst✝³ : DirectSum.GRing 𝒜
inst✝² : DirectSum.GRing ℬ
inst✝¹ : DirectSum.GAlgebra R 𝒜
inst✝ : DirectSum.GAlgebra R ℬ
i j : ι
a : 𝒜 i
b : ℬ j
⊢ (TensorProduct.directSum R R ℬ 𝒜).symm
      ((gradedCommAux R 𝒜 ℬ) ((TensorProduct.directSum R R 𝒜 ℬ) ((lof R ι 𝒜 i) a ⊗ₜ[R] (lof R ι ℬ j) b))) =
    (-1) ^ (j * i) • (lof R ι ℬ j) b ⊗ₜ[R] (lof R ι 𝒜 i) a
tactic: dsimp only [LinearEquiv.trans_apply, LinearEquiv.ofLinear_apply]
state_before: R : Type u_1
ι : Type u_2
A : Type u_3
B : Type u_4
inst✝¹¹ : CommSemiring ι
inst✝¹⁰ : Module ι (Additive ℤˣ)
inst✝⁹ : DecidableEq ι
𝒜 : ι → Type u_5
ℬ : ι → Type u_6
inst✝⁸ : CommRing R
inst✝⁷ : (i : ι) → AddCommGroup (𝒜 i)
inst✝⁶ : (i : ι) → AddCommGroup (ℬ i)
inst✝⁵ : (i : ι) → Module R (𝒜 i)
inst✝⁴ : (i : ι) → Module R (ℬ i)
inst✝³ : DirectSum.GRing 𝒜
inst✝² : DirectSum.GRing ℬ
inst✝¹ : DirectSum.GAlgebra R 𝒜
inst✝ : DirectSum.GAlgebra R ℬ
i j : ι
a : 𝒜 i
b : ℬ j
⊢ (TensorProduct.directSum R R ℬ 𝒜).symm
      ((gradedCommAux R 𝒜 ℬ) ((TensorProduct.directSum R R 𝒜 ℬ) ((lof R ι 𝒜 i) a ⊗ₜ[R] (lof R ι ℬ j) b))) =
    (-1) ^ (j * i) • (lof R ι ℬ j) b ⊗ₜ[R] (lof R ι 𝒜 i) a
state_after: no goals
tactic: rw [TensorProduct.directSum_lof_tmul_lof, gradedCommAux_lof_tmul, Units.smul_def,
    -- Note: #8386 specialized `map_smul` to `LinearEquiv.map_smul` to avoid timeouts.
    ← Int.cast_smul_eq_nsmul R, LinearEquiv.map_smul, TensorProduct.directSum_symm_lof_tmul,
    Int.cast_smul_eq_nsmul, ← Units.smul_def]