916823d
1
2
3
4
5
6
7
8
9
10
import Mathlib open CategoryTheory variable {C : Type*} [Category C] theorem monic_of_comp_monic {X Y Z : C} (g : X ⟶ Y) (f : Y ⟶ Z) [Mono (g ≫ f)] : Mono g := by sorry
