Fuzzy functional dependencies-an overview and a critical discussion

In the context of regular relational databases, functional dependencies have received a lot of attention, since they capture some semantics about the data related to redundancy. Functional dependencies lead to an appropriate design of a database in terms of a set of relations and can make the checking process significantly easier. For about ten years, several proposals to deal with ill-known or weighted data in database management systems have been made and extensions of the relational data model have been proposed accordingly. In this context, the concept of fuzzy functional dependency has emerged, and several definitions have been given. In this paper, a critical overview of different proposals is provided, and the intended semantics and use of fuzzy functional dependencies are particularly discussed