fact: Definition nodes_preserved (cfg cfg' : BDDconfig) := forall (x : BDDvar) (l r node : ad), MapGet _ (fst cfg) node = Some (x, (l, r)) -> MapGet _ (fst cfg') node = Some (x, (l, r)).
imports: Bool Sumbool Arith ZArith NArith Nnat Ndec Ndigits IntMap(Allmaps) Wf_nat BDDvar_ad_nat bdd1 bdd2 bdd3 bdd4