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Journal of Information Science and Engineering, Vol. 22 No. 1, pp. 199-213 (January 2006)

A Study of Disjunctive Information in Fuzzy Relational Databases

Ming-Hua Wang1, Huan-Chao Keh2, Nan-Chen Hsien3 and Tsong-Sheng Wang2
1Department of Information Management
Nanya Institute of Technology
Chungli, 320 Taiwan
2Department of Computer Science and Information Engineering
Tamkang University
Tamshui, 251 Taiwan
3Department of Information Management
National Taipei College of Nursing
Taipei, 112 Taiwan

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 V 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.

Keywords: fuzzy relational database, fuzzy disjunctive information, imprecision, uncertainty, quality of answer

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Received August 15, 2003; revised August 9, 2004; accepted October 12, 2004.
Communicated by Chin-Teng Lin.