Definition mpl_compat_8_def (s : state) : Prop :=
  forall (a c : ad) (pl l : prec_list),
  MapGet prec_list s c = Some l ->
  a <> c -> MapGet prec_list (union_mpl_0 a pl s) c = Some l.

Lemma union_s0d_2_1 : forall (d : preDTA) (pl : prec_list) (s0 s1 : state) (tl : term_list), mpl_compat (M1 prec_list (Npos 1) pl) (M2 prec_list s0 s1) -> state_reconnait d (M1 prec_list (Npos 1) pl) (app (Npos 1) tl) -> state_reconnait d (union_mpl_0 (Npos 1) pl (M2 prec_list s0 s1)) (app (Npos 1) tl).