Finality of Projections in Comma Categories #
We show that fst L R
is final if R
is and that snd L R
is initial if L
is.
instance
CategoryTheory.Comma.final_fst
{A : Type u₁}
[CategoryTheory.Category.{v₁, u₁} A]
{B : Type u₂}
[CategoryTheory.Category.{v₂, u₂} B]
{T : Type u₃}
[CategoryTheory.Category.{v₃, u₃} T]
(L : CategoryTheory.Functor A T)
(R : CategoryTheory.Functor B T)
[R.Final]
:
(CategoryTheory.Comma.fst L R).Final
Equations
- ⋯ = ⋯
instance
CategoryTheory.Comma.initial_snd
{A : Type u₁}
[CategoryTheory.Category.{v₁, u₁} A]
{B : Type u₂}
[CategoryTheory.Category.{v₂, u₂} B]
{T : Type u₃}
[CategoryTheory.Category.{v₃, u₃} T]
(L : CategoryTheory.Functor A T)
(R : CategoryTheory.Functor B T)
[L.Initial]
:
(CategoryTheory.Comma.snd L R).Initial
Equations
- ⋯ = ⋯