Inductive sound_state: state -> Prop :=
  | sound_state_intro: forall st,
      (forall cunit, linkorder cunit prog -> sound_state_base cunit ge st) ->
      sound_state st.Inductive sound_state: state -> Prop :=
  | sound_state_intro: forall st,
      (forall cunit, linkorder cunit prog -> sound_state_base cunit ge st) ->
      sound_state st.

Theorem sound_step: forall st t st', RTL.step ge st t st' -> sound_state st -> sound_state st'.