In the next chapter we discuss the inherent problems associated with representing com- plex database applications using the basic concepts of the ER model. To overcome these problems, additional ‘semantic’ concepts were added to the original ER model resulting in the development of the Enhanced Entity–Relationship (EER) model. In Chapter 12 we describe the main concepts associated with the EER model called specialization/general- ization, aggregation, and composition. We also demonstrate how to convert the ER model shown in Figure 11.1 into the EER model shown in Figure 12.8.