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 BDDzero_preserved :
forall bs bs' : BDDstate, BDDstate_OK bs -> node_preserved_bs bs bs' BDDzero.