fact: Definition RoofHrel' {x y : ob C} (R1 R2 : Roof x y) : hProp := ishinh (RoofTop R1 R2).
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Functors