Problem
In a company each badge has a unique serial number printed on it. The company produces a new badge for each new employee. The employee has possession of the badge as long as the employee works for the company. When the employee's contract with the company ends the employee must return the badge to the company. The company destroys all the returned badges for security reasons. When an employee loses his badge, the employee should let the company know, and then the company produces a new badge for the employee.
Consider the entity set of company's employees and the entity set of the badges. What is the cardinality of the relationship from employee entity set to badge entity set?