Definition predta_coacc_contain_coacc_ads_def_0 (d : preDTA) 
  (a0 a1 : ad) : Prop :=
  coacc d a0 a1 ->
  preDTA_ref_ok d ->
  exists n : nat,
    MapGet bool (power (Map bool) (predta_coacc d a0) (map_mini state d) n)
      a1 = Some true.

Lemma predta_coacc_reverse : forall (n : nat) (d : preDTA) (a b : ad), MapGet bool (power (Map bool) (predta_coacc d a) (map_mini state d) n) b = Some true -> coacc d a b.