Ltac pfullshare_join :=
  elimtype False;
  solve [ eapply pshare_join_full_false1; eauto
    | eapply pshare_join_full_false2; eauto
    | eapply pshare_join_full_false3; eauto
    | eapply pshare_join_full_false4; eauto
    | eapply pshare_pjoin_full_false3; eauto
    | eapply pshare_pjoin_full_false4; eauto
  ].Program Definition split_pshare (sh: pshare) : pshare * pshare :=
  (mk_lifted (fst (Share.split sh)) _, mk_lifted (snd (Share.split sh)) _).

Lemma psplit_pjoin: forall psh psha pshb, split_pshare psh = (psha, pshb) -> join psha pshb psh.