fact: Definition algebra_2cell {XX YY : algebra_ob P} (ff gg : algebra_mor P XX YY) : UU := ∑ (e: pr1 ff = pr1 gg), isalg2cell _ _ e.
imports: UniMath.Foundations.All UniMath.Induction.PolynomialFunctors UniMath.CategoryTheory.Core.Functors UniMath.Induction.FunctorAlgebras_legacy