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