proposition: Lemma axERf s t : prv (fER s t ---> t :/\: (s :\/: fEX (fER s t))).
proof: Proof. exact: axERf'. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base modular_hilbert) CompDecModal.CTL(CTL_def hilbert hilbert_hist)