Lemma BDDneg_1_lemma' : forall (bound : nat) (arg : BDDconfig * ad * BDDneg_memo), BDDconfig_OK (fst (fst arg)) -> config_node_OK (fst (fst arg)) (snd (fst arg)) -> BDDneg_memo_OK_2 (fst (fst arg)) (snd arg) -> (is_internal_node (fst (fst arg)) (snd (fst arg)) -> nat_of_N (var (fst (fst arg)) (snd (fst arg))) < bound) -> fst (BDDneg_1 arg bound) = BDDneg_2 (fst (fst arg)) (snd (fst arg)) bound /\ BDDneg_memo_OK_2 (fst (fst (BDDneg_1 arg bound))) (snd (BDDneg_1 arg bound)).