Instance ClightSem : Semantics :=
    { semG := G; semC := state; semSem := CLC_evsem; the_ge := g }.(* extending Clight_sim to event semantics *)
Inductive ev_star ge: state -> mem -> _ -> state -> mem -> Prop :=
  | ev_star_refl: forall s m,
      ev_star ge s m nil s m
  | ev_star_step: forall s1 m1 ev1 s2 m2 ev2 s3 m3,
      ev_step (CLC_evsem ge) s1 m1 ev1 s2 m2 -> ev_star ge s2 m2 ev2 s3 m3 ->
      ev_star ge s1 m1 (ev1 ++ ev2) s3 m3.(* extending Clight_sim to event semantics *)
Inductive ev_star ge: state -> mem -> _ -> state -> mem -> Prop :=
  | ev_star_refl: forall s m,
      ev_star ge s m nil s m
  | ev_star_step: forall s1 m1 ev1 s2 m2 ev2 s3 m3,
      ev_step (CLC_evsem ge) s1 m1 ev1 s2 m2 -> ev_star ge s2 m2 ev2 s3 m3 ->
      ev_star ge s1 m1 (ev1 ++ ev2) s3 m3.(* extending Clight_sim to event semantics *)
Inductive ev_star ge: state -> mem -> _ -> state -> mem -> Prop :=
  | ev_star_refl: forall s m,
      ev_star ge s m nil s m
  | ev_star_step: forall s1 m1 ev1 s2 m2 ev2 s3 m3,
      ev_step (CLC_evsem ge) s1 m1 ev1 s2 m2 -> ev_star ge s2 m2 ev2 s3 m3 ->
      ev_star ge s1 m1 (ev1 ++ ev2) s3 m3.

Lemma ev_star_two: forall ge s1 m1 ev1 s2 m2 ev2 s3 m3, ev_step (CLC_evsem ge) s1 m1 ev1 s2 m2 -> ev_step (CLC_evsem ge) s2 m2 ev2 s3 m3 -> ev_star ge s1 m1 (ev1 ++ ev2) s3 m3.