You are building a database for your company's Human Resources department.  You want to track employees, their locations, and their job titles.  Each employee is identified by social security number, and you want to store each employee's first name, last name, salary, gender, and performance rating. 

You also want to keep track of each employee's location and job title.  Each employee is assigned to single location and has a single job title.  For each location, you want to store its name, address, state, zipcode, and phone number.  For each job title, you want to store a name, description, education requirement, minimum required salary, and maximum allowable salary.

Every employee except the CEO has one supervisor (the CEO does not have a supervisor).  The database should be able to answer queries like "Who is the supervisor of employee X?", "What are the first and last names of employees who directly supervise at least 4 other employees?", or "Who are all the employees supervised by somebody whose supervisor is employee Z?"

Write a database design outline and entity-relationship diagram for the database.