fact: Fixpoint In_queue_before_data (d d1 : data) (q : queue data) {struct q} : Prop := match q with | empty => True | input d' q' => if eq_data_dec d' d1 then False else d' = d \/ In_queue_before_data d d1 q' end.
imports: DistributedReferenceCounting.machine4.machine DistributedReferenceCounting.machine4.cardinal DistributedReferenceCounting.machine4.comm