English
The instance CatCommSq for OppositeTriangle map with triangleOpEquivalence is provided, ensuring coherence of the opposite triangle operation with equivalences.
Русский
Дано экземпляр CatCommSq для OppositeTriangle, обеспечивающий когерентность противоположной операции треугольника с эквивалентностями.
LaTeX
$$$instCatCommSqOppositeTriangleOpMapTriangleFunctorTriangleOpEquivalence$$$
Lean4
theorem complete_distinguished_triangle_morphism (T₁ T₂ : Triangle Cᵒᵖ) (hT₁ : T₁ ∈ distinguishedTriangles C)
(hT₂ : T₂ ∈ distinguishedTriangles C) (a : T₁.obj₁ ⟶ T₂.obj₁) (b : T₁.obj₂ ⟶ T₂.obj₂)
(comm : T₁.mor₁ ≫ b = a ≫ T₂.mor₁) :
∃ (c : T₁.obj₃ ⟶ T₂.obj₃), T₁.mor₂ ≫ c = b ≫ T₂.mor₂ ∧ T₁.mor₃ ≫ a⟦1⟧' = c ≫ T₂.mor₃ :=
by
rw [mem_distinguishedTriangles_iff] at hT₁ hT₂
obtain ⟨c, hc₁, hc₂⟩ :=
Pretriangulated.complete_distinguished_triangle_morphism₁ _ _ hT₂ hT₁ b.unop a.unop (Quiver.Hom.op_inj comm.symm)
dsimp at c hc₁ hc₂
replace hc₂ := ((opShiftFunctorEquivalence C 1).unitIso.hom.app T₂.obj₁).unop ≫= hc₂
dsimp at hc₂
simp only [assoc, Iso.unop_hom_inv_id_app_assoc] at hc₂
refine ⟨c.op, Quiver.Hom.unop_inj hc₁.symm, Quiver.Hom.unop_inj ?_⟩
apply (shiftFunctor C (1 : ℤ)).map_injective
rw [unop_comp, unop_comp, Functor.map_comp, Functor.map_comp, Quiver.Hom.unop_op, hc₂, ← unop_comp_assoc, ←
unop_comp_assoc, ← opShiftFunctorEquivalence_unitIso_inv_naturality]
simp