proposition: Lemma andSym (T : System) (f g : Formula) : SysPrf T (f /\ g)%nt -> SysPrf T (g /\ f)%nt.
proof: Proof. apply (andSym LNT). Qed.
imports: Coq(Arith Ensembles List) hydras.Ackermann(Languages folProof folProp folLogic3)