induction 1; intuition; subst.
discriminate.
inversion H1; clear H1; subst.
inversion H0; clear H0; subst.
econstructor. econstructor.
intuition.
destruct (IHevalDet_steps c a s s'); eauto.
destruct H0; intuition.
exists x.
exists x0.
intuition.
symmetry in H.
econstructor.
eapply H.
trivial.
Qed.

Lemma evalDet_steps_done_inv : forall (A : Set)(c : Comp A)(a : A) s s',
evalDet_steps (cs_more c s) (cs_done a s') ->
exists c'' s'', evalDet_steps (cs_more c s) (cs_more c'' s'') /\ evalDet_step c'' s'' = (cs_done a s').