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