Section Components.
Variable cfg : BDDconfig.
Hypothesis cfg_OK : BDDconfig_OK cfg.
Definition bs_of_cfg := fst cfg.
Definition share_of_cfg := fst (snd cfg).
Definition fl_of_cfg := fst (snd (snd cfg)).
Definition cnt_of_cfg := fst (snd (snd (snd cfg))).
Definition negm_of_cfg := fst (snd (snd (snd (snd cfg)))).
Definition orm_of_cfg := fst (snd (snd (snd (snd (snd cfg))))).
Definition um_of_cfg := snd (snd (snd (snd (snd (snd cfg))))).

Lemma node_preserved_bs_trans :
forall (bs1 bs2 bs3 : BDDstate) (node : ad),
BDDstate_OK bs1 ->
node_preserved_bs bs1 bs2 node ->
node_preserved_bs bs2 bs3 node -> node_preserved_bs bs1 bs3 node.