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