Introducing keys and integrity rules in a fuzzy relational data model

This paper discusses the fuzzy functional dependency (FFD), which is considered as integrity constraints and used to define /spl theta/-keys. Furthermore, weak/strong /spl theta/-entity integrity rules (/spl theta/-EIRs) are defined as a result of the extension of classical entity integrity rule, and /spl theta/-referential integrity rule (/spl theta/-RIR) is defined as a result of the extension of classical referential integrity rule. These results are deemed important, theoretically and practically, both for integrity constraint enforcement and for fuzzy database design.