proposition: Lemma μ_2_is_Ptd_mor : luinv^{Mon_V}_{I_{Mon_V}} · η ⊗^{Mon_V} η · μ_2 = η.
proof: Proof. rewrite assoc'. apply (z_iso_inv_on_right _ _ _ (nat_z_iso_pointwise_z_iso (leftunitor_nat_z_iso Mon_V) I_{ Mon_V})). cbn. rewrite unitors_coincide_on_unit. etrans. 2: { apply pathsinv0, mhss_second_monoidlaw_aux. } rewrite assoc. apply cancel_postcomposition. apply (bifunctor_equalwhiskers Mon_V). Qed.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Monoidal.WhiskeredBifunctors UniMath.CategoryTheory.Monoidal.Categories UniMath.CategoryTheory.Monoidal.CategoriesOfMonoids UniMath.CategoryTheory.Actegories.Actegories UniMath.CategoryTheory.Actegories.ConstructionOfActegories UniMath.CategoryTheory.Actegories.MorphismsOfActegories UniMath.CategoryTheory.Actegories.CoproductsInActegories UniMath.CategoryTheory.coslicecat UniMath.CategoryTheory.Limits.BinCoproducts UniMath.CategoryTheory.Monoidal.Examples.MonoidalPointedObjects