A New Functional Dependency in a Vague Relational Database Model

In order to model the real world with imprecise and uncertain information, various extensions of the classical relational data model have been studied in literature using fuzzy set theory. However, vague set, as a generalized fuzzy set, has more powerful ability to process fuzzy information than fuzzy set. In this paper, we have proposed a vague relational database model and have defined a new kind of vague functional dependency (called α-vfd) based on the notion of α-equality of tuples and the idea of similarity measure of vague sets. Next, we present a set of sound vague inference rules which are similar to Armstrong’s axioms for the classical case. Finally, partial α-vfd and vague key have been studied with the new notion of α-vfd and also tested with examples.