Figure $4\mathrm{.}12$ shows an example of an EER diagram for a small$-$private$-$airport database; the database is used to keep track of airplanes, their owners, airport employees, and pilots. From the requirements for this database, the following information was collected: Each AIRPLANE has a registration number $[$Reg#$],$ is of a particular plane type $[$OF$\_$TYPE$],$ and is stored in a particular hangar $[$STORED$\_$IN$].$ Each PLANE$\_$TYPE has a model number $[$Model$],$ a capacity $[$Capacity$],$ and a weight $[$Weight$].$ Each HANGAR has a number $[$Number$],$ a capacity $[$Capacity$],$ and a location $[$Location$].$ The database also keeps track of the OWNERs of each plane $[$OWNS$]$ and the EMPLOYEEs who have maintained the plane $[$MAINTAIN$].$ Each relationship instance in OWNS relates an AIRPLANE to an OWNER and includes the purchase date $[$Pdate$].$ Each relationship instance in MAINTAIN relates an EMPLOYEE to a service record $[$SERVICE$].$ Each plane undergoes service many times; hence, it is related by $[$PLANE$\_$SERVICE$]$ to a number of SERVICE records. A SERVICE record includes as attributes the date of maintenance $[$Date$],$ the number of hours spent on the work $[$Hours$],$ and the type of work done $[$Work$\_$code$].$ We use a weak entity type $[$SERVICE$]$ to represent airplane service, because the airplane registration number is used to identify a service record. An OWNER is either a person or a corporation. Hence, we use a union type $($category$)[$OWNER$]$ that is a subset of the union of corporation $[$CORPORATION$]$ and person $[$PERSON$]$ entity types. Both pilots $[$PILOT$]$ and employees $[$EMPLOYEE$]$ are subclasses of PERSON. Each PILOT has specific attributes license number $[$Lic$\_$num$]$ and restrictions $[$Restr$]$; each EMPLOYEE has specific attributes salary $[$Salary$]$ and shift worked $[$Shift$].$ All PERSON entities in the database have data kept on their Social Security number $[$Ssn$],$ name $[$Name$],$ address $[$Address$],$ and telephone number $[$Phone$].$ For CORPORATION entities, the data kept includes name $[$Name$],$ address $[$Address$],$ and telephone number $[$Phone$].$ The database also keeps track of the types of planes each pilot is authorized to fly $[$FLIES$]$ and the types of planes each employee can do maintenance work on $[$WORKS$\_$ON$].$

Show how the SMALL$\_$AIRPORT EER schema in Figure $4\mathrm{.}12$ may be represented as a relational schema.