induction c; intuition; simpl in *; intuition; subst.
inversion H; clear H; subst.
trivial.
destruct (evalDet_step c nil); discriminate.
destruct n; try discriminate.
discriminate.
Qed.

Lemma evalDet_step_done_nil_inv : forall (A : Set)(c : Comp A) a ls,
evalDet_step c nil = (cs_done a ls) ->
ls = nil.