proposition: Lemma is_functor_from_opp_to_opp_opp (A C : precategory) (hsC : has_homsets C) : is_functor (from_opp_to_opp_opp A C hsC).
proof: Proof. split. - now intro F; simpl; apply (nat_trans_eq (has_homsets_opp hsC)); simpl; intro a. - now intros F G H α β; simpl; apply (nat_trans_eq (has_homsets_opp hsC)); simpl; intro a. 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