CoInductive traceinf_sim': traceinf -> traceinf -> Prop :=
| traceinf_sim'_cons: forall t T1 T2,
t <> E0 -> traceinf_sim' T1 T2 -> traceinf_sim' (t *** T1) (t *** T2).

Lemma traceinf_sim'_sim:
forall T1 T2, traceinf_sim' T1 T2 -> traceinf_sim T1 T2.