proposition: Lemma gen_dec A : decidable (gen A).
proof: Proof. case: A => C [[[s t] H]|[[s t] H]|[[s t] H]|[[s t] H]|] /=; eauto using gen_decF, aAU_inU, aAXU_inU, aAR_inU, aAXR_inU, plain_inU, closed_sfc. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base sltype) CompDecModal.CTL(CTL_def gen_def)