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Lemma ageN_comparable {A}  {JA: Join A}{PA: Perm_alg A}{SA: Sep_alg A}{agA: ageable A}{AgeA: Age_alg A}:
forall n (w1 w2 w1' w2': A),
ageN n w1 = Some w1' -> ageN n w2 = Some w2' -> comparable w1 w2 -> comparable w1' w2'.