proposition: Lemma low_high_neq : forall (cfg : BDDconfig) (node : ad), BDDconfig_OK cfg -> is_internal_node cfg node -> N.eqb (low cfg node) (high cfg node) = false.
proof: Proof. intros cfg node H H0. exact (proj1 (internal_node_lemma cfg node H H0)). Qed.
imports: Bool Sumbool Arith ZArith NArith Nnat Ndec Ndigits IntMap(Allmaps) Wf_nat BDDvar_ad_nat bdd1 bdd2