An extended Boyce-Codd normal form in fuzzy relational databases

If the relation schemes of any fuzzy database are not properly designed certain anomaly problems may occur when the fuzzy database is updated or maintained. This is because some undesired relationships exist among attributes. Based on the notions of fuzzy functional dependency (FFD) and /spl theta/-keys, the Boyce-Codd normal form is extended to cope with the anomaly problems caused by partial and transitive FFDs of /spl theta/-prime on some /spl theta/-keys, thus resulting in /spl theta/-fuzzy Boyce-Codd normal form (/spl theta/-FBCNF). Furthermore, the relationship between /spl theta/-FBCNF and other existing fuzzy normal forms is analyzed, showing that /spl theta/-FBCNF reflects the strongest restriction for attributes. Finally an algorithm is provided that can decompose, in a lossless-join manner, any scheme into a number of /spl theta/-FBCNF schemes.