File: Mathlib/CategoryTheory/Triangulated/Triangulated.lean

full_name: CategoryTheory.Triangulated.Octahedron
code: /-- An octahedron is a type of datum whose existence is asserted by
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
structure Octahedron
  {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
  {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
  {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
  {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
  {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C) where
  m₁ : Z₁₂ ⟶ Z₁₃
  m₃ : Z₁₃ ⟶ Z₂₃
  comm₁ : v₁₂ ≫ m₁ = u₂₃ ≫ v₁₃
  comm₂ : m₁ ≫ w₁₃ = w₁₂
  comm₃ : v₁₃ ≫ m₃ = v₂₃
  comm₄ : w₁₃ ≫ u₁₂⟦1⟧' = m₃ ≫ w₂₃
  mem : Triangle.mk m₁ m₃ (w₂₃ ≫ v₁₂⟦1⟧') ∈ distTriang C
goal: Type u_2

full_name: CategoryTheory.Triangulated.Octahedron.mem
code: /-- An octahedron is a type of datum whose existence is asserted by
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
structure Octahedron
  {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
  {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
  {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
  {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
  {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C) where
  m₁ : Z₁₂ ⟶ Z₁₃
  m₃ : Z₁₃ ⟶ Z₂₃
  comm₁ : v₁₂ ≫ m₁ = u₂₃ ≫ v₁₃
  comm₂ : m₁ ≫ w₁₃ = w₁₂
  comm₃ : v₁₃ ≫ m₃ = v₂₃
  comm₄ : w₁₃ ≫ u₁₂⟦1⟧' = m₃ ≫ w₂₃
  mem : Triangle.mk m₁ m₃ (w₂₃ ≫ v₁₂⟦1⟧') ∈ distTriang C
goal: CategoryTheory.Pretriangulated.Triangle.mk self.m₁ self.m₃
    (CategoryTheory.CategoryStruct.comp w₂₃ ((CategoryTheory.shiftFunctor C 1).map v₁₂)) ∈
  CategoryTheory.Pretriangulated.distinguishedTriangles

full_name: CategoryTheory.Triangulated.Octahedron.m₁
code: /-- An octahedron is a type of datum whose existence is asserted by
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
structure Octahedron
  {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
  {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
  {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
  {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
  {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C) where
  m₁ : Z₁₂ ⟶ Z₁₃
  m₃ : Z₁₃ ⟶ Z₂₃
  comm₁ : v₁₂ ≫ m₁ = u₂₃ ≫ v₁₃
  comm₂ : m₁ ≫ w₁₃ = w₁₂
  comm₃ : v₁₃ ≫ m₃ = v₂₃
  comm₄ : w₁₃ ≫ u₁₂⟦1⟧' = m₃ ≫ w₂₃
  mem : Triangle.mk m₁ m₃ (w₂₃ ≫ v₁₂⟦1⟧') ∈ distTriang C
goal: Z₁₂ ⟶ Z₁₃

full_name: CategoryTheory.Triangulated.Octahedron.m₃
code: /-- An octahedron is a type of datum whose existence is asserted by
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
structure Octahedron
  {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
  {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
  {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
  {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
  {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C) where
  m₁ : Z₁₂ ⟶ Z₁₃
  m₃ : Z₁₃ ⟶ Z₂₃
  comm₁ : v₁₂ ≫ m₁ = u₂₃ ≫ v₁₃
  comm₂ : m₁ ≫ w₁₃ = w₁₂
  comm₃ : v₁₃ ≫ m₃ = v₂₃
  comm₄ : w₁₃ ≫ u₁₂⟦1⟧' = m₃ ≫ w₂₃
  mem : Triangle.mk m₁ m₃ (w₂₃ ≫ v₁₂⟦1⟧') ∈ distTriang C
goal: Z₁₃ ⟶ Z₂₃

full_name: CategoryTheory.Triangulated.Octahedron.comm₁
code: /-- An octahedron is a type of datum whose existence is asserted by
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
structure Octahedron
  {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
  {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
  {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
  {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
  {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C) where
  m₁ : Z₁₂ ⟶ Z₁₃
  m₃ : Z₁₃ ⟶ Z₂₃
  comm₁ : v₁₂ ≫ m₁ = u₂₃ ≫ v₁₃
  comm₂ : m₁ ≫ w₁₃ = w₁₂
  comm₃ : v₁₃ ≫ m₃ = v₂₃
  comm₄ : w₁₃ ≫ u₁₂⟦1⟧' = m₃ ≫ w₂₃
  mem : Triangle.mk m₁ m₃ (w₂₃ ≫ v₁₂⟦1⟧') ∈ distTriang C
goal: CategoryTheory.CategoryStruct.comp v₁₂ self.m₁ = CategoryTheory.CategoryStruct.comp u₂₃ v₁₃

full_name: CategoryTheory.Triangulated.Octahedron.comm₃
code: /-- An octahedron is a type of datum whose existence is asserted by
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
structure Octahedron
  {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
  {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
  {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
  {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
  {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C) where
  m₁ : Z₁₂ ⟶ Z₁₃
  m₃ : Z₁₃ ⟶ Z₂₃
  comm₁ : v₁₂ ≫ m₁ = u₂₃ ≫ v₁₃
  comm₂ : m₁ ≫ w₁₃ = w₁₂
  comm₃ : v₁₃ ≫ m₃ = v₂₃
  comm₄ : w₁₃ ≫ u₁₂⟦1⟧' = m₃ ≫ w₂₃
  mem : Triangle.mk m₁ m₃ (w₂₃ ≫ v₁₂⟦1⟧') ∈ distTriang C
goal: CategoryTheory.CategoryStruct.comp v₁₃ self.m₃ = v₂₃

full_name: CategoryTheory.Triangulated.Octahedron.comm₂
code: /-- An octahedron is a type of datum whose existence is asserted by
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
structure Octahedron
  {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
  {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
  {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
  {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
  {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C) where
  m₁ : Z₁₂ ⟶ Z₁₃
  m₃ : Z₁₃ ⟶ Z₂₃
  comm₁ : v₁₂ ≫ m₁ = u₂₃ ≫ v₁₃
  comm₂ : m₁ ≫ w₁₃ = w₁₂
  comm₃ : v₁₃ ≫ m₃ = v₂₃
  comm₄ : w₁₃ ≫ u₁₂⟦1⟧' = m₃ ≫ w₂₃
  mem : Triangle.mk m₁ m₃ (w₂₃ ≫ v₁₂⟦1⟧') ∈ distTriang C
goal: CategoryTheory.CategoryStruct.comp self.m₁ w₁₃ = w₁₂

full_name: CategoryTheory.Triangulated.Octahedron.comm₄
code: /-- An octahedron is a type of datum whose existence is asserted by
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
structure Octahedron
  {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
  {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
  {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
  {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
  {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C) where
  m₁ : Z₁₂ ⟶ Z₁₃
  m₃ : Z₁₃ ⟶ Z₂₃
  comm₁ : v₁₂ ≫ m₁ = u₂₃ ≫ v₁₃
  comm₂ : m₁ ≫ w₁₃ = w₁₂
  comm₃ : v₁₃ ≫ m₃ = v₂₃
  comm₄ : w₁₃ ≫ u₁₂⟦1⟧' = m₃ ≫ w₂₃
  mem : Triangle.mk m₁ m₃ (w₂₃ ≫ v₁₂⟦1⟧') ∈ distTriang C
goal: CategoryTheory.CategoryStruct.comp w₁₃ ((CategoryTheory.shiftFunctor C 1).map u₁₂) =
  CategoryTheory.CategoryStruct.comp self.m₃ w₂₃

full_name: CategoryTheory.Triangulated.instNonemptyOctahedron
code: instance (X : C) :
    Nonempty (Octahedron (comp_id (𝟙 X)) (contractible_distinguished X)
      (contractible_distinguished X) (contractible_distinguished X)) 
goal: Nonempty (CategoryTheory.Triangulated.Octahedron ⋯ ⋯ ⋯ ⋯)

full_name: CategoryTheory.Triangulated.Octahedron.triangle_mor₂
code: /-- The triangle `Z₁₂ ⟶ Z₁₃ ⟶ Z₂₃ ⟶ Z₁₂⟦1⟧` given by an octahedron. -/
@[simps!]
def triangle : Triangle C 
goal: h.triangle.mor₂ = h.m₃

full_name: CategoryTheory.Triangulated.Octahedron.triangle
code: /-- The triangle `Z₁₂ ⟶ Z₁₃ ⟶ Z₂₃ ⟶ Z₁₂⟦1⟧` given by an octahedron. -/
@[simps!]
def triangle : Triangle C 
goal: CategoryTheory.Pretriangulated.Triangle C

full_name: CategoryTheory.Triangulated.Octahedron.triangle_mor₁
code: /-- The triangle `Z₁₂ ⟶ Z₁₃ ⟶ Z₂₃ ⟶ Z₁₂⟦1⟧` given by an octahedron. -/
@[simps!]
def triangle : Triangle C 
goal: h.triangle.mor₁ = h.m₁

full_name: CategoryTheory.Triangulated.Octahedron.triangle_mor₃
code: /-- The triangle `Z₁₂ ⟶ Z₁₃ ⟶ Z₂₃ ⟶ Z₁₂⟦1⟧` given by an octahedron. -/
@[simps!]
def triangle : Triangle C 
goal: h.triangle.mor₃ = CategoryTheory.CategoryStruct.comp w₂₃ ((CategoryTheory.shiftFunctor C 1).map v₁₂)

full_name: CategoryTheory.Triangulated.Octahedron.triangle_obj₃
code: /-- The triangle `Z₁₂ ⟶ Z₁₃ ⟶ Z₂₃ ⟶ Z₁₂⟦1⟧` given by an octahedron. -/
@[simps!]
def triangle : Triangle C 
goal: h.triangle.obj₃ = Z₂₃

full_name: CategoryTheory.Triangulated.Octahedron.triangle_obj₁
code: /-- The triangle `Z₁₂ ⟶ Z₁₃ ⟶ Z₂₃ ⟶ Z₁₂⟦1⟧` given by an octahedron. -/
@[simps!]
def triangle : Triangle C 
goal: h.triangle.obj₁ = Z₁₂

full_name: CategoryTheory.Triangulated.Octahedron.triangle_obj₂
code: /-- The triangle `Z₁₂ ⟶ Z₁₃ ⟶ Z₂₃ ⟶ Z₁₂⟦1⟧` given by an octahedron. -/
@[simps!]
def triangle : Triangle C 
goal: h.triangle.obj₂ = Z₁₃

full_name: CategoryTheory.Triangulated.Octahedron.triangleMorphism₁_hom₁
code: /-- The first morphism of triangles given by an octahedron. -/
@[simps]
def triangleMorphism₁ : Triangle.mk u₁₂ v₁₂ w₁₂ ⟶ Triangle.mk u₁₃ v₁₃ w₁₃ 
goal: h.triangleMorphism₁.hom₁ = CategoryTheory.CategoryStruct.id X₁

full_name: CategoryTheory.Triangulated.Octahedron.triangleMorphism₁
code: /-- The first morphism of triangles given by an octahedron. -/
@[simps]
def triangleMorphism₁ : Triangle.mk u₁₂ v₁₂ w₁₂ ⟶ Triangle.mk u₁₃ v₁₃ w₁₃ 
goal: CategoryTheory.Pretriangulated.Triangle.mk u₁₂ v₁₂ w₁₂ ⟶ CategoryTheory.Pretriangulated.Triangle.mk u₁₃ v₁₃ w₁₃

full_name: CategoryTheory.Triangulated.Octahedron.triangleMorphism₁_hom₃
code: /-- The first morphism of triangles given by an octahedron. -/
@[simps]
def triangleMorphism₁ : Triangle.mk u₁₂ v₁₂ w₁₂ ⟶ Triangle.mk u₁₃ v₁₃ w₁₃ 
goal: h.triangleMorphism₁.hom₃ = h.m₁

full_name: CategoryTheory.Triangulated.Octahedron.triangleMorphism₁_hom₂
code: /-- The first morphism of triangles given by an octahedron. -/
@[simps]
def triangleMorphism₁ : Triangle.mk u₁₂ v₁₂ w₁₂ ⟶ Triangle.mk u₁₃ v₁₃ w₁₃ 
goal: h.triangleMorphism₁.hom₂ = u₂₃

full_name: CategoryTheory.Triangulated.Octahedron.triangleMorphism₂_hom₁
code: /-- The second morphism of triangles given an octahedron. -/
@[simps]
def triangleMorphism₂ : Triangle.mk u₁₃ v₁₃ w₁₃ ⟶ Triangle.mk u₂₃ v₂₃ w₂₃ 
goal: h.triangleMorphism₂.hom₁ = u₁₂

full_name: CategoryTheory.Triangulated.Octahedron.triangleMorphism₂_hom₃
code: /-- The second morphism of triangles given an octahedron. -/
@[simps]
def triangleMorphism₂ : Triangle.mk u₁₃ v₁₃ w₁₃ ⟶ Triangle.mk u₂₃ v₂₃ w₂₃ 
goal: h.triangleMorphism₂.hom₃ = h.m₃

full_name: CategoryTheory.Triangulated.Octahedron.triangleMorphism₂_hom₂
code: /-- The second morphism of triangles given an octahedron. -/
@[simps]
def triangleMorphism₂ : Triangle.mk u₁₃ v₁₃ w₁₃ ⟶ Triangle.mk u₂₃ v₂₃ w₂₃ 
goal: h.triangleMorphism₂.hom₂ = CategoryTheory.CategoryStruct.id X₃

full_name: CategoryTheory.Triangulated.Octahedron.triangleMorphism₂
code: /-- The second morphism of triangles given an octahedron. -/
@[simps]
def triangleMorphism₂ : Triangle.mk u₁₃ v₁₃ w₁₃ ⟶ Triangle.mk u₂₃ v₂₃ w₂₃ 
goal: CategoryTheory.Pretriangulated.Triangle.mk u₁₃ v₁₃ w₁₃ ⟶ CategoryTheory.Pretriangulated.Triangle.mk u₂₃ v₂₃ w₂₃

full_name: CategoryTheory.Triangulated.Octahedron.ofIso
code: /-- When two diagrams are isomorphic, an octahedron for one gives an octahedron for the other. -/
def ofIso {X₁' X₂' X₃' Z₁₂' Z₂₃' Z₁₃' : C} (u₁₂' : X₁' ⟶ X₂') (u₂₃' : X₂' ⟶ X₃') (u₁₃' : X₁' ⟶ X₃')
    (comm' : u₁₂' ≫ u₂₃' = u₁₃')
    (e₁ : X₁ ≅ X₁') (e₂ : X₂ ≅ X₂') (e₃ : X₃ ≅ X₃')
    (comm₁₂ : u₁₂ ≫ e₂.hom = e₁.hom ≫ u₁₂') (comm₂₃ : u₂₃ ≫ e₃.hom = e₂.hom ≫ u₂₃')
    (v₁₂' : X₂' ⟶ Z₁₂') (w₁₂' : Z₁₂' ⟶ X₁'⟦(1 : ℤ)⟧)
    (h₁₂' : Triangle.mk u₁₂' v₁₂' w₁₂' ∈ distTriang C)
    (v₂₃' : X₃' ⟶ Z₂₃') (w₂₃' : Z₂₃' ⟶ X₂'⟦(1 : ℤ)⟧)
    (h₂₃' : Triangle.mk u₂₃' v₂₃' w₂₃' ∈ distTriang C)
    (v₁₃' : X₃' ⟶ Z₁₃') (w₁₃' : Z₁₃' ⟶ X₁'⟦(1 : ℤ)⟧)
    (h₁₃' : Triangle.mk (u₁₃') v₁₃' w₁₃' ∈ distTriang C)
    (H : Octahedron comm' h₁₂' h₂₃' h₁₃') : Octahedron comm h₁₂ h₂₃ h₁₃ 
goal: CategoryTheory.Triangulated.Octahedron comm h₁₂ h₂₃ h₁₃

full_name: CategoryTheory.IsTriangulated.octahedron_axiom
code: /-- A triangulated category is a pretriangulated category which satisfies
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
class IsTriangulated : Prop where
  /-- the octahedron axiom (TR 4) -/
  octahedron_axiom :
    ∀ {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
      {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
      {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
      {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
      {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C),
      Nonempty (Octahedron comm h₁₂ h₂₃ h₁₃)
goal: Nonempty (CategoryTheory.Triangulated.Octahedron comm h₁₂ h₂₃ h₁₃)

full_name: CategoryTheory.IsTriangulated
code: /-- A triangulated category is a pretriangulated category which satisfies
the octahedron axiom (TR 4), see https://stacks.math.columbia.edu/tag/05QK -/
class IsTriangulated : Prop where
  /-- the octahedron axiom (TR 4) -/
  octahedron_axiom :
    ∀ {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
      {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
      {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
      {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
      {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C),
      Nonempty (Octahedron comm h₁₂ h₂₃ h₁₃)
goal: Prop

full_name: CategoryTheory.Triangulated.someOctahedron'
code: /-- A choice of octahedron given by the octahedron axiom. -/
def someOctahedron' [IsTriangulated C] : Octahedron comm h₁₂ h₂₃ h₁₃ 
goal: CategoryTheory.Triangulated.Octahedron comm h₁₂ h₂₃ h₁₃

full_name: CategoryTheory.Triangulated.someOctahedron
code: /-- A choice of octahedron given by the octahedron axiom. -/
def someOctahedron [IsTriangulated C]
    {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C}
    {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : u₁₂ ≫ u₂₃ = u₁₃)
    {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
    {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ X₂⟦(1 : ℤ)⟧} (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
    {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ X₁⟦(1 : ℤ)⟧} (h₁₃ : Triangle.mk u₁₃ v₁₃ w₁₃ ∈ distTriang C) :
    Octahedron comm h₁₂ h₂₃ h₁₃ 
goal: CategoryTheory.Triangulated.Octahedron comm h₁₂ h₂₃ h₁₃

full_name: CategoryTheory.IsTriangulated.mk'
code: /-- Constructor for `IsTriangulated C` which shows that it suffices to obtain an octahedron
for a suitable isomorphic diagram instead of the given diagram. -/
lemma IsTriangulated.mk' (h : ∀ ⦃X₁' X₂' X₃' : C⦄ (u₁₂' : X₁' ⟶ X₂') (u₂₃' : X₂' ⟶ X₃'),
    ∃ (X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C) (u₁₂ : X₁ ⟶ X₂) (u₂₃ : X₂ ⟶ X₃) (e₁ : X₁' ≅ X₁) (e₂ : X₂' ≅ X₂)
    (e₃ : X₃' ≅ X₃) (_ : u₁₂' ≫ e₂.hom = e₁.hom ≫ u₁₂)
    (_ : u₂₃' ≫ e₃.hom = e₂.hom ≫ u₂₃)
    (v₁₂ : X₂ ⟶ Z₁₂) (w₁₂ : Z₁₂ ⟶ X₁⟦1⟧) (h₁₂ : Triangle.mk u₁₂ v₁₂ w₁₂ ∈ distTriang C)
    (v₂₃ : X₃ ⟶ Z₂₃) (w₂₃ : Z₂₃ ⟶ X₂⟦1⟧) (h₂₃ : Triangle.mk u₂₃ v₂₃ w₂₃ ∈ distTriang C)
    (v₁₃ : X₃ ⟶ Z₁₃) (w₁₃ : Z₁₃ ⟶ X₁⟦1⟧)
      (h₁₃ : Triangle.mk (u₁₂ ≫ u₂₃) v₁₃ w₁₃ ∈ distTriang C),
        Nonempty (Octahedron rfl h₁₂ h₂₃ h₁₃)) :
    IsTriangulated C 
goal: CategoryTheory.IsTriangulated C