intuition.
destruct c; simpl in *.
inversion H; clear H; subst.
econstructor; eauto.
case_eq (evalDet_step c ls); intuition; rewrite H0 in H; discriminate.
destruct (shiftOut ls n). destruct p. discriminate.
discriminate.
discriminate.
Qed.

(* Specifications: *)
Lemma evalDet_step_more_sublist : forall (A : Set)(c : Comp A) c' ls ls',
evalDet_step c ls = (cs_more c' ls') ->
exists ls'', ls = ls'' ++ ls'.