induction 1; intros; subst.
inversion H0; clear H0; subst.
intuition.
inversion H2; clear H2; subst.
eapply IHevalDet_steps;
trivial.
Qed.

Theorem evalDet_steps_done_func : forall (A : Set) x (a a' : A) s s',
evalDet_steps x (cs_done a s) ->
evalDet_steps x (cs_done a' s') ->
(a = a' /\ s = s').