Definition dest_below (dst: destination) (g: generator) : Prop :=
  match dst with
  | For_set sd => Plt (sd_temp sd) g.(gen_next)
  | _ => True
  end.Remark dest_for_val_below: forall g, dest_below For_val g.Remark dest_for_effect_below: forall g, dest_below For_effects g.

Lemma dest_below_le: forall dst g1 g2, dest_below dst g1 -> Ple g1.(gen_next) g2.(gen_next) -> dest_below dst g2.