1. Based on the information here, draw a domain model class diagram for the MLS system. Be sure to consider what information needs to be included versus information that is not in the problem domain. For example, is detailed information about the owner, such as his employer or his credit history, required in the MLS system? Is that information required regarding a potential buyer?

2. Draw a second domain model class diagram that adds the following specifications. First, there are two types of listings: a listing for sale and a listing for lease. Additionally, a listing might include no structures, such as vacant land, or it might include more than one structure, such as the main house and a guest house, each with separate values for square footage, number of bedrooms, and number of bathrooms.

3. Draw a third domain model class diagram that assumes a listing might have multiple owners. Additionally, a listing might be shared by two or more agents, and the percentage of the commission that each agent gets from the sale can be different for each agent.

4. Consider that a real estate listing goes through several different states over time. For example,

it might be a new listing, a mature listing, a revised listing, an under contract listing, and a sold listing. Draw a state machine diagram for a listing object based on this information. Include transition names and be sure to consider all of the possible transitions. For example, can a new listing transition directly to an under contract listing?

5. Based on the domain classes you identified, draw a domain model class diagram showing domain classes with attributes and associations with multiplicity.

6. Using the noun technique, read through this case and identify all the nouns that may be important for this system. You may also find it helpful to read back through the case descriptions in the previous chapters.

7. Once you have identified all the nouns, identify which are classes and which are attributes of these primary classes. Begin constructing a class diagram based on the classes and attributes you have identified.

8. Finalize the class diagram, including all your classes, attributes, primary keys, relationships, and multiplicity constraints.

9. Modify the diagram (Figure 4-25) to incorporate the changes under consideration. You may need to use association classes and generalization/specialization (inheritance).

10.Are  a set of abstract and concrete classes needed to represent variations among cell phones? Why or why not?