intuition.
edestruct (evalDet_dec).
eauto.
destruct H0.
econstructor.
eauto.
econstructor.
eauto.
Qed.

Lemma evalDet_steps_done_support_singleton_h : forall (A : Set)(x1 x2 : comp_state A),
evalDet_steps x1 x2 ->
forall (c : Comp A) a s,
x1 = (cs_more c nil) ->
x2 = (cs_done a s) ->
getSupport c = a :: nil.