proposition: Lemma prv_ER : prv (ER fF (fF ---> fF)).
proof: Proof. rewrite /ER. apply: AU_ind. Intro. Apply. drop. exact: axI. Intro. drop. exact: ax_serial. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base modular_hilbert) CompDecModal.CTL(CTL_def hilbert)