Design an EER diagram for a library as described below. Show relevant constraints. $(40$ points$)$

Each employee has an SSN$,$ fname, Iname, and address.

An employee is classified into one of three categories: managerial, research, and floor. Floor employees paid by the hour and have an hourly wage rate. The other two categories have a salary. Research workers pecialty, while managerial workers have a job title.

c$.$ Customers are identified by their card number, and also have a fname, Iname, and address.

d$.$ Each book is identified by its LCN $($Library of Congress Number$).$ It has a title, and one or more authors.

e$.$ An author has as a key an author code, since fname, Iname does not suffice. We also keep track of their b date and date of death.

f$.$ Customers may check out books. We keep track of the date it was checked out, as well as the date of retu it has been returned.

g$.$ Each time a book is checked out, we want to track which employee was involved in that transaction. Chec out a book can be handled by floor or research staff, but not managerial staff.

h$.$ Each member of the floor staff has exactly one member of the managerial staff as a supervisor.

Your EER diagram of the library database. Make sure to include in your diagram the following whenever possi

Entity types and relationship types

Union$/$Category

Specialization$/$Generalization

Cardinality constraints

Discuss any assumptions and justify your EER design choices

$2-$ Cardinality ratios often dictate the detailed design of a database. The cardinality ratio depends on the realworld meaning of the entity types involved and is defined by the specific application. For the binary relationships below, suggest cardinality ratios based on the common$-$sense meaning of the entity types. Clear state any assumptions you make. $(20$ points$)$