proposition: Lemma rlabel_Fs p : {subset label (root (Frag p)) <= Fs D}.
proof: Proof. rewrite label_root. case: p => /= _ [C inD]. apply/subP => /=. exact: bigU1. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base sltype) CompDecModal.CTL(CTL_def dags)