proposition: Lemma subst_closed s n u : closed s -> subst s n u = s.
proof: Proof. now intros ->. Qed.
imports: Undecidability.Shared.Libs.PSL(Vectors) Coq(Vector List) Undecidability.L(L LTactics L_facts Functions.Eval) Undecidability.L.Util(NaryApp)