Theorem: CategoryTheory.Pretriangulated.complete_distinguished_triangle_morphism₁
File: Mathlib/CategoryTheory/Triangulated/Pretriangulated.lean

Proof steps:
state_before: 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
b : T₁.obj₂ ⟶ T₂.obj₂
c : T₁.obj₃ ⟶ T₂.obj₃
comm : T₁.mor₂ ≫ c = b ≫ T₂.mor₂
⊢ ∃ a, T₁.mor₁ ≫ b = a ≫ T₂.mor₁ ∧ T₁.mor₃ ≫ (shiftFunctor C 1).map a = c ≫ T₂.mor₃
state_after: case intro.intro
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
b : T₁.obj₂ ⟶ T₂.obj₂
c : T₁.obj₃ ⟶ T₂.obj₃
comm : T₁.mor₂ ≫ c = b ≫ T₂.mor₂
a : T₁.rotate.obj₃ ⟶ T₂.rotate.obj₃
ha₁ : T₁.rotate.mor₂ ≫ a = c ≫ T₂.rotate.mor₂
ha₂ : T₁.rotate.mor₃ ≫ (shiftFunctor C 1).map b = a ≫ T₂.rotate.mor₃
⊢ ∃ a, T₁.mor₁ ≫ b = a ≫ T₂.mor₁ ∧ T₁.mor₃ ≫ (shiftFunctor C 1).map a = c ≫ T₂.mor₃
tactic: obtain ⟨a, ⟨ha₁, ha₂⟩⟩ := complete_distinguished_triangle_morphism _ _
    (rot_of_distTriang _ hT₁) (rot_of_distTriang _ hT₂) b c comm
state_before: case intro.intro
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
b : T₁.obj₂ ⟶ T₂.obj₂
c : T₁.obj₃ ⟶ T₂.obj₃
comm : T₁.mor₂ ≫ c = b ≫ T₂.mor₂
a : T₁.rotate.obj₃ ⟶ T₂.rotate.obj₃
ha₁ : T₁.rotate.mor₂ ≫ a = c ≫ T₂.rotate.mor₂
ha₂ : T₁.rotate.mor₃ ≫ (shiftFunctor C 1).map b = a ≫ T₂.rotate.mor₃
⊢ ∃ a, T₁.mor₁ ≫ b = a ≫ T₂.mor₁ ∧ T₁.mor₃ ≫ (shiftFunctor C 1).map a = c ≫ T₂.mor₃
state_after: case intro.intro.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
b : T₁.obj₂ ⟶ T₂.obj₂
c : T₁.obj₃ ⟶ T₂.obj₃
comm : T₁.mor₂ ≫ c = b ≫ T₂.mor₂
a : T₁.rotate.obj₃ ⟶ T₂.rotate.obj₃
ha₁ : T₁.rotate.mor₂ ≫ a = c ≫ T₂.rotate.mor₂
ha₂ : T₁.rotate.mor₃ ≫ (shiftFunctor C 1).map b = a ≫ T₂.rotate.mor₃
⊢ T₁.mor₁ ≫ b = (shiftFunctor C 1).preimage a ≫ T₂.mor₁

case intro.intro.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
b : T₁.obj₂ ⟶ T₂.obj₂
c : T₁.obj₃ ⟶ T₂.obj₃
comm : T₁.mor₂ ≫ c = b ≫ T₂.mor₂
a : T₁.rotate.obj₃ ⟶ T₂.rotate.obj₃
ha₁ : T₁.rotate.mor₂ ≫ a = c ≫ T₂.rotate.mor₂
ha₂ : T₁.rotate.mor₃ ≫ (shiftFunctor C 1).map b = a ≫ T₂.rotate.mor₃
⊢ T₁.mor₃ ≫ (shiftFunctor C 1).map ((shiftFunctor C 1).preimage a) = c ≫ T₂.mor₃
tactic: refine ⟨(shiftFunctor C (1 : ℤ)).preimage a, ⟨?_, ?_⟩⟩