intuition.
inversion H; clear H; subst.
econstructor.
eapply evalDet_steps_app_eq.
eauto.
Qed.

Lemma evalDet_steps_done_nil_inv_h : forall (A : Set)(x y : comp_state A),
evalDet_steps x y ->
forall (c : Comp A) a ls,
x = (cs_more c nil) ->
y = (cs_done a ls) ->
ls = nil.