proposition: Lemma SumStrength1' : θ_Strength1_int θ.
proof: Proof. intro X. apply nat_trans_eq_alt; intro x; simpl. etrans; [apply CoproductOfArrows_comp|]. apply pathsinv0, Coproduct_endo_is_identity; intro i. etrans; [ apply (CoproductOfArrowsIn _ _ (CD (λ i, pr1 (pr1 (H1 i) X) x))) |]. etrans; [| apply id_left]. apply cancel_postcomposition, (nat_trans_eq_pointwise (S11' i X) x). Qed.
imports: UniMath.Foundations.PartD UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.FunctorCategory UniMath.CategoryTheory.whiskering UniMath.CategoryTheory.PrecategoryBinProduct UniMath.CategoryTheory.PointedFunctors UniMath.CategoryTheory.PointedFunctorsComposition UniMath.SubstitutionSystems.Signatures UniMath.CategoryTheory.Limits.Coproducts UniMath.SubstitutionSystems.Notation UniMath.CategoryTheory.Chains.Chains UniMath.CategoryTheory.Chains.OmegaCocontFunctors UniMath.CategoryTheory.Limits.Products