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# Object Modeling Constraints (Identify) - Exercise

## Basic Object Modeling Constraints using Class Diagram

### Course project: modeling basic associations

Objective: Draw class diagrams based on excerpts from the course project problem statement.

### Exercise scoring

This exercise is worth a total of 10 points.

### Background/overview

This is the second exercise in the course project.

### Instructions

Given the two excerpts below from the course project problem statement, create a class diagram for each of the two excerpts. Be sure to:
1. Identify the classes involved.
2. Identify the associations between the classes.
3. Draw and name the associations.
4. Assign multiplicity to each end of each association.
5. Add constraints where needed to account for all the rules documented in the problem statement.

### Hints

1. It is valid for there to be more than one association between the same pair of classes.
2. Use a verb or verb phrase. Try to use the active form whenever possible.
3. Remember to watch for how the time frame can effect your multiplicity choices. Sometimes a combination of multiplicity and constraints is required to clarify the rules.

### Excerpt 1

The event floor plan defines the layout for all the shows for the same event. All the show seating charts for the same event must refer to the same event floor plan.
(Focus on the event floor plan and the show seating chart for now. In later lessons, we will add the events and shows.)

### Excerpt 2

Customers may hold seats while they try to figure out which ones they want to purchase. This prevents more than one customer from attempting to purchase a seat at the same time. Customers may also return the seats and get their money back.

Step 1
In the text area below, type Course project, part 2