proposition: Lemma pre_composition_essentially_surjective : essentially_surjective (pre_composition_functor A B C H).
proof: Proof. intros F p' f. apply f. exists (GG F). apply idtoiso. apply is_preimage_for_pre_composition. Qed.
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.Univalence UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Univalence UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.FunctorCategory UniMath.CategoryTheory.whiskering