$4-$ You have just been hired as a consultant for a big airplane manufacturer. They want you to completely redesign their database system. Talking with the people in the company, you get the following information.

The database contains information about employees, factories and parts.

Each employee has a social security number $($SSN$),$ name, and salary. An employee is uniquely identified by his$/$her SSN$.$

Each factory has an id$,$ a name, and a budget. The id uniquely identifies a factory.

Each part has an id and a name. The id uniquely identifies a part.

Each employee reports to at most one other employee.

Each employee works in at least one factory.

Each part is manufactured in exactly one factory.

a$)$ Draw the E$-$R diagram for the above application. $(10$ pts$.)$

b$)$ Create the database schema for the given details above. $(10$ pts$.)$