Fuzzy normal forms and a dependency-preserving decomposition into /spl theta/-F3NF

摘要

In a fuzzy data model where imprecision of both attribute values and relationships among domain elements is taken into account, problems of data redundancy and update anomalies which are similar to those in classical databases are still found to exist. To cope with these problems, a number of fuzzy normal forms have been defined, based on fuzzy functional dependency, to serve as theoretical guidelines for fuzzy relational database design. This results in the notions of /spl theta/-keys, fuzzy first normal form (F1NF), /spl theta/-fuzzy second normal form (/spl theta/-F2NF), /spl theta/-fuzzy third normal form (/spl theta/-F3NF), and /spl theta/-fuzzy Boyce-Codd normal form (/spl theta/-FBCNF). Furthermore, the scheme decomposition into /spl theta/-F3NF is discussed in the light of the dependency-preserving property.