Fuzzy Database Approaches

Abstract

Both the problem of representation and the treatment of imprecise information have been widely discussed. Many references can be found in the corresponding bibliography. Nevertheless, all the known models aimed at solving this problem have their own advantages, disadvantages, and constraints. The term imprecision encompasses various meanings, which might be interesting to highlight. It alludes to the facts that the information available can be incomplete, that we don’t know whether the information is true (uncertainty), that we are totally unaware of the information (unknown), or that such information is not applicable to a given entity (undefined). Sometimes these meanings are not disjunctive and can be combined in certain types of information. This chapter deals with the main published models aimed at solving the problem of representation and treatment of imprecise information in relational databases. This problem is not trivial, because it requires relations structure modification, and thus, the operations on these relations also need to be modified. To allow the storage of imprecise information and the making of an inaccurate query of such information, a wide variety of case studies that do not occur in the classic model, without imprecision, is required.