(* * Copyright (c) 2009-2011, Andrew Appel, Robert Dockins and Aquinas Hobor. * *)
(** The prototypical example of a psepalg is the positive shares, which are just the lifted basic shares. *)
Definition pshare : Type := lifted Share.Join_ba.
Instance Join_pshare: Join pshare := @Join_lift _ _.
Instance Perm_pshare : Perm_alg pshare := Perm_lift Share.pa.
Instance Canc_pshare : Canc_alg pshare := @Canc_lift _ _ Share.ca.
Instance Disj_pshare : Disj_alg pshare := @Disj_lift _ _ Share.da.
Instance Pos_pshare : Pos_alg pshare := @Pos_lift _ _.
Definition pshare_sh : pshare -> share := @lifted_obj share Share.Join_ba.
Coercion pshare_sh : pshare >-> share.
Instance EqDec_pshare : EqDec pshare := pshare_eq_dec.
Definition pfullshare : pshare :=
mk_lifted fullshare top_share_nonunit.
Proof with auto.
unfold pshare.
apply lifted_full. auto with typeclass_instances.
apply fullshare_full.
Qed.

Lemma pshare_join_full_false4: forall (p1: pshare) sh3,
join Share.top (lifted_obj p1) sh3 -> False.