proposition: Lemma functor_comp_id (A B : precategory) (G : functor A B) (a a' : A) (f : a --> a') (g : a' --> a) : f · g = identity _ -> #G f · #G g = identity _ .
proof: Proof. intro e. intermediate_path (#G (identity a )). - rewrite <- e. apply (! functor_comp _ _ _). - apply functor_id_id. apply idpath. Qed.
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.MoreFoundations.PartA UniMath.MoreFoundations.Univalence UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.TransportMorphisms UniMath.CategoryTheory.Core.Univalence