Definition BDDor :=
  BDDor_1 gc cfg ul node1 node2
    (S
       (max (nat_of_N (node_height cfg node1))
          (nat_of_N (node_height cfg node2)))).

Lemma BDDor_var_le : Nleb (node_height (fst BDDor) (snd BDDor)) (BDDvar_max (node_height cfg node1) (node_height cfg node2)) = true.