context EventService inv NbEventService: EventService.allInstances --> size <= 3 and EventService.allInstances --> size >0 context EventService inv NbEventServiceNurse: context EventService inv NbEventServiceNurse: EventService.allInstances --> forAll(es:EventService | ((es.nurse --> size <=5) and (es.patient --> size <=15))) context Patient inv NbPatientEventService: Patient.allInstances --> forAll(p:Patient | ((p.eventService --> size =1) and (p.nurse --> size =1))) context Nurse inv NbNurseEventService: Nurse allInstances --> forAll(n: Nurse | ((n eventService --> size =1) and (n patient --> size <=3))Nurse.n.n.3))) context EventService inv ExNurseEventService: EventService.allInstances --> forAll(es | es.patient --> notEmpty implies es.nurse --> notEmpty)