English
The functor sending a distinguished triangle in C to its opposite triangle in Cᵒᵖ is an equivalence, preserving the distinguished structure up to isomorphism.
Русский
Функтор, отправляющий выделенный треугольник в C в противоположный треугольник в Cᵒᵖ, является эквивалентностью, сохраняющей выделенную структуру до изоморфизма.
LaTeX
$$$\\text{triangleOpEquivalence}: (Triangle\\; C)^{op} \\simeq Triangle\\; (C^{op})$$$
Lean4
/-- An anti-equivalence between the categories of triangles in `C` and in `Cᵒᵖ`.
A triangle in `Cᵒᵖ` shall be distinguished iff it correspond to a distinguished
triangle in `C` via this equivalence. -/
@[simps]
noncomputable def triangleOpEquivalence : (Triangle C)ᵒᵖ ≌ Triangle Cᵒᵖ
where
functor := TriangleOpEquivalence.functor C
inverse := TriangleOpEquivalence.inverse C
unitIso := TriangleOpEquivalence.unitIso C
counitIso := TriangleOpEquivalence.counitIso C