Comparison of entity with fuzzy data types in fuzzy object-oriented databases

Aiming at distinguishing entities, the concept of entity comparison plays an important role in object management in object-oriented databases as well as object-oriented knowledge bases. In order to model uncertain data and complex-valued attributes as well as complex relationships among objects/classes, fuzzy object-oriented databases have been introduced. In this paper, we identify two levels of entities in fuzzy object-oriented databases, which are fuzzy classes and fuzzy objects. Based on the semantic measure of fuzzy data, we identify several possible relationships between fuzzy entities being compared, and propose a more general way to compare the objects and classes with fuzzy data types in the fuzzy object-oriented databases. We introduce the notion of equivalence degree of two fuzzy entities. We apply this notion to compare two fuzzy entities so that we know to which extent two objects or two classes refer to the same real-world entity.