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