(* Autor(s): Andrej Dudenhefner (1) Affiliation(s): (1) Saarland University, Saarbrücken, Germany *)
Local Notation "p ≃ q" := (poly_eq p q) (at level 65).

Lemma poly_eq_nilI {a p} : a = 0 -> p ≃ [] -> a :: p ≃ [].