End RtRft.
Hint Resolve rt_refl.
Definition laterR {A} `{ageable A} : relation A := clos_trans A age.
Definition necR   {A} `{ageable A} : relation A := clos_refl_trans A age.
Require Coq.Wellfounded.Wellfounded.

Lemma laterR_wf {A} `{ageable A} :
well_founded (transp _ laterR).