proposition: Proposition idtoiso_opp {C : category} {x y : C} (p : x = y) : pr1 (@idtoiso (C^op) _ _ p) = pr1 (@idtoiso C _ _ (!p)).
proof: Proof. induction p ; cbn. apply idpath. Qed.
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Univalence UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.FunctorCategory