Module: Mathlib.CategoryTheory.Triangulated.Pretriangulated

Goal state before:
pp: case refine_1
C : Type u
inst✝⁴ : Category.{v, u} C
inst✝³ : HasZeroObject C
inst✝² : HasShift C ℤ
inst✝¹ : Preadditive C
inst✝ : ∀ (n : ℤ), (shiftFunctor C n).Additive
hC : Pretriangulated C
T₁ T₂ : Triangle C
hT₁ : T₁ ∈ distinguishedTriangles
hT₂ : T₂ ∈ distinguishedTriangles
e₁ : T₁.obj₁ ≅ T₂.obj₁
e₃ : T₁.obj₃ ≅ T₂.obj₃
comm : T₁.mor₃ ≫ (shiftFunctor C 1).map e₁.hom = e₃.hom ≫ T₂.mor₃
h :
  ∃ e',
    e'.hom.hom₁ = Arrow.Hom.left (Arrow.isoMk ((shiftFunctor C (-1)).mapIso e₃) e₁ ⋯).hom ∧
      e'.hom.hom₂ = Arrow.Hom.right (Arrow.isoMk ((shiftFunctor C (-1)).mapIso e₃) e₁ ⋯).hom
e : T₁.invRotate ≅ T₂.invRotate := h.choose
h₁ : e.hom.hom₁ = (shiftFunctor C (-1)).map e₃.hom
h₂ : e₁.hom = e.hom.hom₂
h₃ :
  (T₁.mor₂ ≫ (shiftFunctorCompIsoId C (-1) 1 ⋯).inv.app T₁.3) ≫ (shiftFunctor C 1).map e.hom.hom₁ =
    e.hom.hom₃ ≫ T₂.mor₂ ≫ (shiftFunctorCompIsoId C (-1) 1 ⋯).inv.app T₂.3
h₄ :
  e₃.hom ≫ (shiftFunctorCompIsoId C (-1) 1 isoTriangleOfIso₁₃._proof_4).inv.app T₂.obj₃ =
    (shiftFunctorCompIsoId C (-1) 1 isoTriangleOfIso₁₃._proof_4).inv.app T₁.obj₃ ≫
      (shiftFunctor C 1).map ((shiftFunctor C (-1)).map e₃.hom)
⊢ T₁.mor₁ ≫ (Triangle.π₃.mapIso e).hom = e₁.hom ≫ T₂.mor₁

pp: case refine_2
C : Type u
inst✝⁴ : Category.{v, u} C
inst✝³ : HasZeroObject C
inst✝² : HasShift C ℤ
inst✝¹ : Preadditive C
inst✝ : ∀ (n : ℤ), (shiftFunctor C n).Additive
hC : Pretriangulated C
T₁ T₂ : Triangle C
hT₁ : T₁ ∈ distinguishedTriangles
hT₂ : T₂ ∈ distinguishedTriangles
e₁ : T₁.obj₁ ≅ T₂.obj₁
e₃ : T₁.obj₃ ≅ T₂.obj₃
comm : T₁.mor₃ ≫ (shiftFunctor C 1).map e₁.hom = e₃.hom ≫ T₂.mor₃
h :
  ∃ e',
    e'.hom.hom₁ = Arrow.Hom.left (Arrow.isoMk ((shiftFunctor C (-1)).mapIso e₃) e₁ ⋯).hom ∧
      e'.hom.hom₂ = Arrow.Hom.right (Arrow.isoMk ((shiftFunctor C (-1)).mapIso e₃) e₁ ⋯).hom
e : T₁.invRotate ≅ T₂.invRotate := h.choose
h₁ : e.hom.hom₁ = (shiftFunctor C (-1)).map e₃.hom
h₂ : e₁.hom = e.hom.hom₂
h₃ :
  (T₁.mor₂ ≫ (shiftFunctorCompIsoId C (-1) 1 ⋯).inv.app T₁.3) ≫ (shiftFunctor C 1).map e.hom.hom₁ =
    e.hom.hom₃ ≫ T₂.mor₂ ≫ (shiftFunctorCompIsoId C (-1) 1 ⋯).inv.app T₂.3
h₄ :
  e₃.hom ≫ (shiftFunctorCompIsoId C (-1) 1 isoTriangleOfIso₁₃._proof_4).inv.app T₂.obj₃ =
    (shiftFunctorCompIsoId C (-1) 1 isoTriangleOfIso₁₃._proof_4).inv.app T₁.obj₃ ≫
      (shiftFunctor C 1).map ((shiftFunctor C (-1)).map e₃.hom)
⊢ T₁.mor₂ ≫ e₃.hom = (Triangle.π₃.mapIso e).hom ≫ T₂.mor₂

Tactic:
· convert! e.hom.comm₂ using 2

Goal state after:
case refine_2
C : Type u
inst✝⁴ : Category.{v, u} C
inst✝³ : HasZeroObject C
inst✝² : HasShift C ℤ
inst✝¹ : Preadditive C
inst✝ : ∀ (n : ℤ), (shiftFunctor C n).Additive
hC : Pretriangulated C
T₁ T₂ : Triangle C
hT₁ : T₁ ∈ distinguishedTriangles
hT₂ : T₂ ∈ distinguishedTriangles
e₁ : T₁.obj₁ ≅ T₂.obj₁
e₃ : T₁.obj₃ ≅ T₂.obj₃
comm : T₁.mor₃ ≫ (shiftFunctor C 1).map e₁.hom = e₃.hom ≫ T₂.mor₃
h :
  ∃ e',
    e'.hom.hom₁ = Arrow.Hom.left (Arrow.isoMk ((shiftFunctor C (-1)).mapIso e₃) e₁ ⋯).hom ∧
      e'.hom.hom₂ = Arrow.Hom.right (Arrow.isoMk ((shiftFunctor C (-1)).mapIso e₃) e₁ ⋯).hom
e : T₁.invRotate ≅ T₂.invRotate := h.choose
h₁ : e.hom.hom₁ = (shiftFunctor C (-1)).map e₃.hom
h₂ : e₁.hom = e.hom.hom₂
h₃ :
  (T₁.mor₂ ≫ (shiftFunctorCompIsoId C (-1) 1 ⋯).inv.app T₁.3) ≫ (shiftFunctor C 1).map e.hom.hom₁ =
    e.hom.hom₃ ≫ T₂.mor₂ ≫ (shiftFunctorCompIsoId C (-1) 1 ⋯).inv.app T₂.3
h₄ :
  e₃.hom ≫ (shiftFunctorCompIsoId C (-1) 1 isoTriangleOfIso₁₃._proof_4).inv.app T₂.obj₃ =
    (shiftFunctorCompIsoId C (-1) 1 isoTriangleOfIso₁₃._proof_4).inv.app T₁.obj₃ ≫
      (shiftFunctor C 1).map ((shiftFunctor C (-1)).map e₃.hom)
⊢ T₁.mor₂ ≫ e₃.hom = (Triangle.π₃.mapIso e).hom ≫ T₂.mor₂