proposition: Lemma existSimp (T : System) (f : Formula) (v : nat): SysPrf T f -> SysPrf T (exH v, f)%nt.
proof: Proof. apply (existSimp LNT). Qed.
imports: Coq(Arith Ensembles List) hydras.Ackermann(Languages folProof folProp folLogic3)