In, you were asked to draw an entity-relationship diagram describing Happy Cruise Lines' business environment. We now report that Happy Cruise Lines has been acquired by MegaShip Lines, Inc., which has a fleet of oil tankers, container ships, and automobile transport ships. Thus, with the addition of Happy's cruise ships, MegaShip Lines will have four kinds of ships.

a. Draw an object-oriented generalization diagram, including aggregation relationships as needed, to represent MegaShip's new business environment, with the following attributes and operations. All of MegaShip's ships have ship number, ship name, year built, weight, miles traveled, and next overhaul date attributes. In addition, cruise ships have passenger capacity and next health inspection date; oil tankers have oil capacity, container ships have number of containers, and automobile transport ships have number of automobile attributes. An operation determines the next overhaul date for all of the ships in the same manner. Another operation determines the next health inspection date for cruise ships. An operation calculates the next date for a ship to be refueled. This operation is the same for oil tankers, container ships, and automobile transport ships, but is different for cruise ships because of safety precautions regarding the passengers. Oil tankers are composed of a hull, one or more engines, and one or more oil storage tanks. An attribute of hull is length, an attribute of engine is horsepower, and an attribute of oil storage tank is capacity.

b. Add the information given about cruise ships, cruises, etc., in, to the diagram in part a, constructing a complete object-oriented class diagram.