Section selectors.
Variable (j: juicy_mem).
Definition m_dry := match j with mkJuicyMem m _ _ _ _ _ => m end.
Definition m_phi := match j with mkJuicyMem _ phi _ _ _ _ => phi end.

Lemma age1_joinx {A}  {JA: Join A}{PA: Perm_alg A}{agA: ageable A}{AgeA: Age_alg A} : forall phi1 phi2 phi3 phi1' phi2' phi3',
age phi1 phi1' -> age phi2 phi2' -> age phi3 phi3' ->
join phi1 phi2 phi3 -> join phi1' phi2' phi3'.