E (G : Functor D E) (F : Functor C D) : identity G oR F = 1. Proof. path_natural_transformation; auto with morphism. Qed.
Require Import Category.Core Functor.Core Functor.Identity Functor.Composition.Core NaturalTransformation.Core NaturalTransformation.Identity NaturalTransformation.Composition.Core NaturalTransformation.Paths.