intuition.
edestruct dat_exists_bind2.
eauto.
eauto.
eapply leRat_trans.
2:{
eapply eqRat_impl_leRat.
symmetry.
eapply (bind_low_tree_approx_same_inv).
eauto.
eauto.
eauto.
eauto.
}
edestruct dat_exists.
eapply well_formed_Bind; eauto.
eapply leRat_trans.
eapply eqRat_impl_leRat.
symmetry.
eapply low_tree_approx_same_inv.
eauto.
eauto.
apply lowDistApprox_dat_better_le.
inversion H3; clear H3; subst.
intuition.
eapply datMap_depth_better.
4:{
eapply dat_correct_bind_same_h.
eapply H4.
eauto.
trivial.
intuition.
eapply evalDet_steps_done_nil_inv; eauto.
eauto.
}
eapply dat_better_refl.
intuition.
eapply dat_correct_dat_better.
eapply H7.
eapply H8.
trivial.
eapply H6.
auto.
Grab Existential Variables.
eapply bind_eq_dec; eauto.
Qed.

Lemma dat_correct_bind_same: forall (A B : Set)(c1 : Comp B)(c2 : B -> Comp A) n t,
well_formed_comp c1 ->
dat_correct (Bind c1 c2) n t ->
dat_correct_bind c1 c2 n t.