proposition: Fact vec_list_In n v p : In (vec_pos v p) (@vec_list n v).
proof: Proof. revert p; induction v; intros p; invert pos p; auto. Qed.
imports: Arith Lia List Permutation Undecidability.Shared.Libs.DLW.Utils(utils) Undecidability.Shared.Libs.DLW.Vec(pos)