Definition BDDneg :=
  BDDneg_1 gc cfg ul node (S (nat_of_N (node_height cfg node))).

Lemma BDDneg_is_neg : bool_fun_eq (bool_fun_of_BDD (fst BDDneg) (snd BDDneg)) (bool_fun_neg (bool_fun_of_BDD cfg node)).