 Letting formula_24 be a chain of formula_3 elements, we have formula_26 and formula_27 There is only one linear extension (the identity mapping), and both polynomials have leading term formula_28.Letting formula_24 be an antichain of formula_3 incomparable elements, we have formula_31.Since any bijection formula_20 is (strictly) order-preserving, there are formula_23 linear extensions, and both polynomials reduce to the leading term formula_34.