-- Mathlib/CategoryTheory/Monoidal/Braided/Basic.lean
theorem leftUnitor_monoidal (X₁ X₂ : C) :
    (λ_ X₁).hom ⊗ (λ_ X₂).hom =
      tensorμ (𝟙_ C) X₁ (𝟙_ C) X₂ ≫ ((λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂)) ≫ (λ_ (X₁ ⊗ X₂)).hom

Proof state:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
⊢ (λ_ X₁).hom ⊗ (λ_ X₂).hom = tensorμ (𝟙_ C) X₁ (𝟙_ C) X₂ ≫ (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Tactic:
dsimp only [tensorμ]

Result:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
⊢ (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Proof state:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
⊢ (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫ 𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ (ρ_ X₁).hom ▷ X₂

Tactic:
monoidal

Result:
no goals

Proof state:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
this :
  (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫ 𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ (ρ_ X₁).hom ▷ X₂
⊢ (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫ 𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ (ρ_ X₁).hom ▷ X₂ =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Tactic:
clear this

Result:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
⊢ (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫ 𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ (ρ_ X₁).hom ▷ X₂ =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Proof state:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
⊢ (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
      𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ ((β_ X₁ (𝟙_ C)).hom ≫ (λ_ X₁).hom) ▷ X₂ =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Tactic:
monoidal

Result:
no goals

Proof state:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
⊢ (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Tactic:
have :
  (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
      (𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv) ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ ((ρ_ X₁).hom ▷ X₂) := by
  monoidal

Result:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
this :
  (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫ 𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ (ρ_ X₁).hom ▷ X₂
⊢ (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Proof state:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
⊢ (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫ 𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ (ρ_ X₁).hom ▷ X₂ =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Tactic:
rw [← braiding_leftUnitor]

Result:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
⊢ (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
      𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ ((β_ X₁ (𝟙_ C)).hom ≫ (λ_ X₁).hom) ▷ X₂ =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Proof state:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
this :
  (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫ 𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ (ρ_ X₁).hom ▷ X₂
⊢ (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom

Tactic:
rw [this]

Result:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
inst✝¹ : MonoidalCategory C
inst✝ : BraidedCategory C
X₁ X₂ : C
this :
  (λ_ X₁).hom ⊗ (λ_ X₂).hom =
    (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫ 𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ (ρ_ X₁).hom ▷ X₂
⊢ (α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫ 𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫ (λ_ ((X₁ ⊗ 𝟙_ C) ⊗ X₂)).hom ≫ (ρ_ X₁).hom ▷ X₂ =
    ((α_ (𝟙_ C) X₁ (𝟙_ C ⊗ X₂)).hom ≫
        𝟙_ C ◁ (α_ X₁ (𝟙_ C) X₂).inv ≫
          𝟙_ C ◁ (β_ X₁ (𝟙_ C)).hom ▷ X₂ ≫ 𝟙_ C ◁ (α_ (𝟙_ C) X₁ X₂).hom ≫ (α_ (𝟙_ C) (𝟙_ C) (X₁ ⊗ X₂)).inv) ≫
      (λ_ (𝟙_ C)).hom ▷ (X₁ ⊗ X₂) ≫ (λ_ (X₁ ⊗ X₂)).hom