fact: Definition Roof (x y : ob C) : UU := ∑ D : (∑ z : ob C, C⟦z, x⟧ × C⟦z, y⟧), (SOM (pr1 D) x (dirprod_pr1 (pr2 D))).
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Functors