A Study of Disjunctive Information in Fuzzy Relational Databases

This paper proposes a logical reconstruction of the classical fuzzy relational database model to accommodate fuzzy disjunctive information. In query processing, we use two supplementary measurements, matching information and extra information, to model the concepts of imprecision and uncertainty, respectively. We also use these two supplementary measurements to determine the quality of answers to the query. The answers to the query thus contain sure answers and maybe answers. In addition, we discuss the redundancy problem by presenting a complete set of fuzzy relational algebra with fuzzy disjunctive information. The proposed extended fuzzy relational database model preserves the properties – uniquely-determined and well-defined properties of relational algebra to ensure that the manipulative power of the proposed model is the same as that of the classical fuzzy relational database model.