proposition: Lemma axAXdef s : prv (fAX s <--> ~~: fEX (~~: s)).
proof: Proof. exact: axAXdef'. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base modular_hilbert) CompDecModal.CTL(CTL_def hilbert)