Proof with auto.
intros H0 H1 H2. unfold do_unfold'.
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding1_sound;auto].
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding2_sound;auto].
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding3_sound;auto].
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding4_sound;auto].
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding6_sound;auto].
auto.
Qed.

Lemma MEqual_InElem2: forall s t,
M.Equal s t ->
forall x, In x (M.elements t) -> In x (M.elements s).