proposition: Lemma axN s t : prv (fAX (s ---> t) ---> fAX s ---> fAX t).
proof: Proof. apply: rAIL. rewrite -> axABBA. apply: rRegAX. by rule axAcase. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base modular_hilbert) CompDecModal.CTL(CTL_def hilbert)