proposition: Lemma iffTrans (T : System) (f g h : Formula): SysPrf T (f <-> g)%fol -> SysPrf T (g <-> h)%fol -> SysPrf T (f <-> h)%fol.
proof: Proof. apply (iffTrans LNN). Qed.
imports: Coq(Arith Ensembles List) LibHyps(LibHyps) hydras(MoreLibHyps NewNotations)