Module Share : SHARE_MODEL := tree_shares.Share.Definition share : Type := Share.t.Instance pa_share : Perm_alg share := Share.pa.Instance sa_share : Sep_alg share := Share.sa.Instance ca_share : Canc_alg share := Share.ca.Definition emptyshare : share := Share.bot.Definition fullshare : share := Share.top.

Lemma rel_join2 : forall a x y s, nonidentity a -> join (rel a x) (rel a y) s -> exists z, s = rel a z /\ join x y z.