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 split_join : forall x1 x2 x, split x = (x1,x2) -> join x1 x2 x.