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(* modify it under the terms of the GNU Lesser General Public License *)
(* as published by the Free Software Foundation; either version 2.1   *)
(* of the License, or (at your option) any later version.             *)
(*                                                                    *)
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(* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the      *)
(* GNU General Public License for more details.                       *)
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(* 02110-1301 USA                                                     *)
Require Export DistributedReferenceCounting.machine3.alternate.
Require Export DistributedReferenceCounting.machine3.invariant0.
Require Export DistributedReferenceCounting.machine3.invariant1.
Require Export DistributedReferenceCounting.machine3.invariant2.
Require Export DistributedReferenceCounting.machine3.invariant3.
Require Export DistributedReferenceCounting.machine3.invariant4.
Unset Standard Proposition Elimination Names.
(* Changes - proof of  1  for false_rt_D_queue. - proof of  1  for  legal_alternate. - owner_st_positive and its proof. *)
Section INVARIANT5.
(* In this file, we establish the following inequality Int + Sum copy + Sum dec - Sum inc_dec >= 0  *)
(* The message queue between a site and the owner has a particular structure.  Messages dec and inc_dec are alternated. *)

Lemma legal_alternate :
forall (s : Site) (c : Config),
legal c ->
alternate (bm c s owner) /\ (rt c s = false -> D_queue (bm c s owner)).