induction c; intuition; simpl in *.
intuition; subst.
inversion H; clear H; subst.
trivial.
destruct (evalDet_step c s1); discriminate.
destruct (shiftOut s1 n); [ destruct p ; discriminate | discriminate ].
discriminate.
Qed.

(* Specifications: *)
Lemma evalDet_step_done_ls_eq : forall (A : Set)(c : Comp A)(a2 : A) s1 s2,
evalDet_step c s1 = (cs_done a2 s2) ->
s1 = s2.