proposition: Lemma axEXD s t : prv (EX (s :\/: t) <--> EX s :\/: EX t).
proof: Proof. rewrite /EX. rewrite -> dmO, <- axABBA, dmA. reflexivity. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base modular_hilbert) CompDecModal.CTL(CTL_def hilbert)