proposition: Lemma left_whisker_with_runitor {C : category} (M : monoidal C) : triangle_identity'' ru_{M} α_{M}.
proof: Proof. red; intros x y. assert (aux := right_whisker_with_lunitor (monoidal_swapped M) y x). cbn in aux. rewrite <- aux. rewrite assoc. etrans. { apply cancel_postcomposition. apply monoidal_associatorisolaw. } apply id_left. Qed.
imports: UniMath.Foundations.All UniMath.MoreFoundations.Notations UniMath.MoreFoundations.PartA UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.PrecategoryBinProduct UniMath.CategoryTheory.Monoidal.WhiskeredBifunctors UniMath.CategoryTheory.Adjunctions.Core UniMath.CategoryTheory.Equivalences.Core UniMath.CategoryTheory.Equivalences.FullyFaithful UniMath.CategoryTheory.opp_precat