(* démo si mapget power predta_coacc = true alors l'état est coaccessible *)

Lemma predta_coacc_rev :
forall (d : preDTA) (a : ad) (m : Map bool) (b : ad),
MapGet bool (predta_coacc d a m) b = Some true ->
ensemble_base state d m ->
(exists a0 : ad,
(exists s : state,
(exists c : ad,
(exists p : prec_list,
MapGet state d a0 = Some s /\
MapGet prec_list s c = Some p /\
prec_occur p b /\ MapGet bool m a0 = Some true)))) \/
a = b.