proposition: Fact vec_zero_plus v : vec_plus vec_zero v = v.
proof: Proof. apply vec_pos_ext. intros p; unfold vec_zero, vec_plus. repeat rewrite vec_pos_set; auto. Qed.
imports: Arith Lia List Permutation Undecidability.Shared.Libs.DLW.Utils(utils) Undecidability.Shared.Libs.DLW.Vec(pos)