proposition: Lemma ϕ₂_ϕ₁_id: ϕ₂ i (id a) □ ϕ₁ i (id a) = id b.
proof: Proof. set (H':= pr2 (pr1 (pr2 (pr1 (pr2 i))))). simpl in H'. specialize (H' _ (id _ ) (id _ ) (id _ )). simpl in H'. rewrite <- ϕo_id. apply comp_compose2'. apply H'. apply comp_compose2. apply T_I_l. Qed.
imports: UniMath.Folds.UnicodeNotations UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.Foundations.UnivalenceAxiom UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.Folds.folds_precat UniMath.Folds.from_precats_to_folds_and_back