Triangulated Categories #
This file contains the definition of triangulated categories, which are pretriangulated categories which satisfy the octahedron axiom.
An octahedron is a type of datum whose existence is asserted by the octahedron axiom (TR 4). The input is given by the following diagram:
u₁₃ v₂₃
X₁ ────> X₃ ────> Z₂₃ Z₁₂⟦1⟧
\ ^ \ \ ^
u₁₂\ u₂₃/ \v₁₃ \w₂₃ /v₁₂⟦1⟧'
V / V V /
X₂ Z₁₃ X₂⟦1⟧
\ \ ^
v₁₂\ \w₁₃ /u₁₂⟦1⟧'
V V /
Z₁₂ ───> X₁⟦1⟧
w₁₂
where u₁₂ ≫ u₂₃ = u₁₃ and (u₁₂,v₁₂,w₁₂), (u₁₃,v₁₃,w₁₃) and (u₂₃,v₂₃,w₂₃)
are distinguished triangles.. An Octahedron for this data consists of
maps m₁ : Z₁₂ ⟶ Z₁₃ and m₃ : Z₁₃ ⟶ Z₂₃ such that (m₁, m₃, w₂₃ ≫ v₁₂⟦1⟧') is
a distinguished triangle and the completed diagram commutes:
u₁₃ v₂₃
X₁ ────> X₃ ────> Z₂₃ ────> Z₁₂⟦1⟧
\ ^ \ ^ \ ^
u₁₂\ u₂₃/ \v₁₃ /m₃ \w₂₃ /v₁₂⟦1⟧'
V / V / V /
X₂ Z₁₃ X₂⟦1⟧
\ ^ \ ^
v₁₂\ /m₁ \w₁₃ /u₁₂⟦1⟧'
V / V /
Z₁₂ ───> X₁⟦1⟧
w₁₂
m₁is the morphismaof (TR 4) as presented in Stacks.m₃is the morphismbof (TR 4) as presented in Stacks.- mem : Pretriangulated.Triangle.mk self.m₁ self.m₃ (CategoryStruct.comp w₂₃ ((shiftFunctor C 1).map v₁₂)) ∈ Pretriangulated.distinguishedTriangles
Instances For
The triangle Z₁₂ ⟶ Z₁₃ ⟶ Z₂₃ ⟶ Z₁₂⟦1⟧ given by an octahedron.
Equations
- h.triangle = CategoryTheory.Pretriangulated.Triangle.mk h.m₁ h.m₃ (CategoryTheory.CategoryStruct.comp w₂₃ ((CategoryTheory.shiftFunctor C 1).map v₁₂))
Instances For
The first morphism of triangles given by an octahedron.
Equations
- h.triangleMorphism₁ = { hom₁ := CategoryTheory.CategoryStruct.id X₁, hom₂ := u₂₃, hom₃ := h.m₁, comm₁ := ⋯, comm₂ := ⋯, comm₃ := ⋯ }
Instances For
The second morphism of triangles given an octahedron.
Equations
- h.triangleMorphism₂ = { hom₁ := u₁₂, hom₂ := CategoryTheory.CategoryStruct.id X₃, hom₃ := h.m₃, comm₁ := ⋯, comm₂ := ⋯, comm₃ := ⋯ }
Instances For
When two diagrams are isomorphic, an octahedron for one gives an octahedron for the other.
Equations
- One or more equations did not get rendered due to their size.
Instances For
An octahedron' is a type of datum whose existence follows from the octahedron axiom (TR 4). It is a rotated version of an octahedron. The input is given by the following diagram:
v₁₂ u₁₃ w₂₃
Z₁₂ ────> X₁ ─────> X₃ ─────> Z₂₃⟦1⟧
^ \ ^ \
v₁₃/ u₁₂\ u₂₃/ \w₁₃
/ V / V
Z₁₃ X₂ Z₁₃⟦1⟧
^ \
v₂₃/ \w₁₂
/ V
Z₂₃ Z₁₂⟦1⟧
where u₁₂ ≫ u₂₃ = u₁₃ and (v₁₂,u₁₂,w₁₂), (v₁₃,u₁₃,w₁₃) and (v₂₃,u₂₃,w₂₃)
are distinguished triangles.. An Octahedron' for this data consists of
maps m₁ : Z₁₂ ⟶ Z₁₃ and m₃ : Z₁₃ ⟶ Z₂₃ such that (m₁, m₃, v₂₃ ≫ w₁₂) is
a distinguished triangle and the completed diagram commutes:
v₁₂ u₁₃ w₂₃
Z₁₂ ────> X₁ ─────> X₃ ─────> Z₂₃⟦1⟧
\ ^ \ ^ \ ^
m₁\ v₁₃/ u₁₂\ u₂₃/ \w₁₃ /m₃⟦1⟧'
V / V / V /
Z₁₃ X₂ Z₁₃⟦1⟧
\ ^ \ ^
m₃\ v₂₃/ \w₁₂ /m₁⟦1⟧'
V / V /
Z₂₃ ────> Z₁₂⟦1⟧
m₁is the morphismaof (TR 4) as presented in Stacks.m₁is the morphismbof (TR 4) as presented in Stacks.- mem : Pretriangulated.Triangle.mk self.m₁ self.m₃ (CategoryStruct.comp v₂₃ w₁₂) ∈ Pretriangulated.distinguishedTriangles
Instances For
The triangle Z₁₂ ⟶ Z₁₃ ⟶ Z₂₃ ⟶ Z₁₂⟦1⟧ given by an Octahedron'.
Equations
- CategoryTheory.Triangulated.Octahedron'.triangle comm h₁₂ h₂₃ h₁₃ h = CategoryTheory.Pretriangulated.Triangle.mk h.m₁ h.m₃ (CategoryTheory.CategoryStruct.comp v₂₃ w₁₂)
Instances For
The first morphism of triangles given by an Octahedron'.
Equations
- CategoryTheory.Triangulated.Octahedron'.triangleMorphism₁ comm h₁₂ h₂₃ h₁₃ h = { hom₁ := h.m₁, hom₂ := CategoryTheory.CategoryStruct.id X₁, hom₃ := u₂₃, comm₁ := ⋯, comm₂ := ⋯, comm₃ := ⋯ }
Instances For
The second morphism of triangles given by an Octahedron'.
Equations
- CategoryTheory.Triangulated.Octahedron'.triangleMorphism₂ comm h₁₂ h₂₃ h₁₃ h = { hom₁ := h.m₃, hom₂ := u₁₂, hom₃ := CategoryTheory.CategoryStruct.id X₃, comm₁ := ⋯, comm₂ := ⋯, comm₃ := ⋯ }
Instances For
A triangulated category is a pretriangulated category which satisfies the octahedron axiom (TR 4).
- octahedron_axiom {X₁ X₂ X₃ Z₁₂ Z₂₃ Z₁₃ : C} {u₁₂ : X₁ ⟶ X₂} {u₂₃ : X₂ ⟶ X₃} {u₁₃ : X₁ ⟶ X₃} (comm : CategoryStruct.comp u₁₂ u₂₃ = u₁₃) {v₁₂ : X₂ ⟶ Z₁₂} {w₁₂ : Z₁₂ ⟶ (shiftFunctor C 1).obj X₁} (h₁₂ : Pretriangulated.Triangle.mk u₁₂ v₁₂ w₁₂ ∈ Pretriangulated.distinguishedTriangles) {v₂₃ : X₃ ⟶ Z₂₃} {w₂₃ : Z₂₃ ⟶ (shiftFunctor C 1).obj X₂} (h₂₃ : Pretriangulated.Triangle.mk u₂₃ v₂₃ w₂₃ ∈ Pretriangulated.distinguishedTriangles) {v₁₃ : X₃ ⟶ Z₁₃} {w₁₃ : Z₁₃ ⟶ (shiftFunctor C 1).obj X₁} (h₁₃ : Pretriangulated.Triangle.mk u₁₃ v₁₃ w₁₃ ∈ Pretriangulated.distinguishedTriangles) : Nonempty (Triangulated.Octahedron comm h₁₂ h₂₃ h₁₃)
the octahedron axiom (TR 4)
Instances
A choice of octahedron given by the octahedron axiom.
Equations
- CategoryTheory.Triangulated.someOctahedron comm h₁₂ h₂₃ h₁₃ = ⋯.some
Instances For
A choice of octahedron' given by the octahedron axiom.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Constructor for IsTriangulated C which shows that it suffices to obtain an octahedron
for a suitable isomorphic diagram instead of the given diagram.