proposition: Lemma subtractv_disjoint_subset : forall {G : CFGV} {vc : VarSym G} (vs l1 l2 : list (vType vc)), subset l1 l2 -> disjoint l1 (subtractv vs l2).
proof: Proof. unfold subtractv. introv ss i j. allrw in_diff; sp. Qed.
imports: CFGV Omega Eqdep_dec