fact: Definition ptd_mor (F G : ptd_obj) : UU := ∑ α : F ⟹ G, is_ptd_mor α.
imports: UniMath.Foundations.PartD UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.FunctorCategory