Given the information below, create the fully labeled Crow's Foot ERD using a specialization hierarchy where appropriate (use Visio). The ERD must contain all primary keys, foreign keys, and main attributes. Business rules are defined as follows:

A small on-line university consists of several departments. Only one employee can chair a department. Each department is chaired by one employee.

All people related to the university are classified into three categories: Employees, Students, and Alumni. Employees could also be students.

All people share common attributes - ID, first and last name, and e-mail. Some attributes are unique. The list of such attributes includes but is not limited to the following: the employee's salary, the student's GPA, and the year of graduation (Alumni).

Also, employees are subdivided into two groups: professors and staff. Each professor has a rank. A staff representative has a position.