Definition traces (state: Type): Type := Ensemble (trace state).
Definition traces_app {state: Type} (d1 d2: traces state): traces state :=
fun tr =>
(exists tr1 tr2, d1 tr1 /\ d2 tr2 /\ tr = stream_app tr1 tr2) \/
(exists tr1, d1 tr1 /\ (end_state tr1 NonTerminating \/ end_state tr1 Error) /\ tr = tr1).
Fixpoint traces_power {state: Type} (d: traces state) (n: nat): traces state :=
match n with
| 0 => is_empty_stream
| S n => traces_app (traces_power d n) d
end.
Definition traces_pstar {state: Type} (d: traces state): traces state :=
fun tr => exists n, traces_power d n tr.
Definition traces_pomega {state: Type} (d: traces state): traces state :=
fun tr => exists f, tr = stream_capp f /\ forall n, d (f n).

Lemma traces_app_mono {state: Type}: forall (d1 d2 d3 d4: traces state),
Included _ d1 d3 ->
Included _ d2 d4 ->
Included _ (traces_app d1 d2) (traces_app d3 d4).