fact: Definition isEpi {x y : C} (f : x --> y) : UU := ∏ (z : C) (g h : y --> z), f · g = f · h -> g = h.
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.FunctorCategory UniMath.CategoryTheory.Subcategory.Core UniMath.CategoryTheory.Core.Functors