(* 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_nilE {a p} : a :: p ≃ [] -> a = 0 /\ p ≃ [].