Fuzzy EER Concepts

Abstract

As mentioned in Chapter 2, the enhanced entity-relationship (EER) model has largely enriched the usefulness and expressiveness of the ER model by introducing the concepts such as subclass and superclass, generalization and specialization, shared subclass and category, attribute inheritance, etc., as conceptual model constructs (Dos Santos, et al., 1979; Scheuermann, et al., 1979; Elmasri, et al., 1985; Teorey, et al., 1986; Gogolla, et al., 1991). Further, these constructs can also be extended using fuzzy logic to account for the conceptual-level uncertainty and imprecision due to fuzziness inherent in corresponding semantics (Kerre and Chen, 1995; Chen and Kerre, 1998). In this chapter, we will discuss fuzzy extensions to the EER concepts around the notion of subclass and superclass. In section 5.1, fuzzy subclass and superclass are described. In section 5.2, a pair of dual concepts related to subclass and superclass, namely, specialization and generalization, are fuzzified. Particular attention is paid to the attribute-defined specialization and generalization. Section 5.3 describes fuzzy extensions to the concepts of shared subclass and category, which is another pair of concepts related to subclass and superclass. Finally, in section 5.4, the issues of inheritance are addressed, including the inheritance of attributes and relationships.