proposition: Lemma nat_α_whisker_assoc A B C D (F : A ⟶ B) (G H : B ⟶ C) (J : C ⟶ D) (η : G ⟹ H) : to (nat_α F H J) ∙ J ⊳ (η ⊲ F) ≈ (J ⊳ η) ⊲ F ∙ to (nat_α F G J).
proof: Proof. simpl; intros; cat. Qed.
imports: Category.Lib Category.Theory.Category Category.Theory.Isomorphism Category.Theory.Functor Category.Theory.Natural.Transformation Category.Instance.Sets