Langlib{aⁿbⁿcⁿ} is not context-free #
The language lang_eq_eq = {aⁿbⁿcⁿ | n ∈ ℕ} is not context-free. The pumping lemma
(CF_pumping) applied to aⁿ⁺¹bⁿ⁺¹cⁿ⁺¹ yields a decomposition u v x y z where v y
omits some letter, so pumping unbalances the counts of the other two.