UML Class Diagram of a car rental company

This example has the next 4 entities:

1. Car Rental Company: company itself, which is the “whole“.
2. Car: cars owned by the company.
3. Rental: rental entity (like contract), which is the “whole” for Car and Renter entities.
4. Renter: a person who rent car.

All of the connections are composition. The system has the next generalization connections:

• Car Rental Company – Car: the company can have 0 or many cars; a car can have only 1 company.
• Car Rental Company – Rental: the company can have 0 or many rentals; a renal can have only 1 company.
• Car Rental Company – Renter: the company can have 0 or many renters; a renter assigned only o 1 company.
• Rental – Car: 1 rental can be assigned to 1 car and vise versa.
• Rental – Renter: each rental can have only 1 renter but a renter can have 0 or many rental.