Multiargument Relationships in Possibilistic Databases

In the paper we consider the possible coexistence of associations between k < n attributes of the n-ary relationship. The analysis is carried out using the theory of functional dependencies. We assume that attribute values are represented by means of possibility distributions. According to the representation of data the notion of fuzzy functional dependency has been appropriately extended. Its level is evaluated with the use of possibility and necessity measures. The dependencies between all n attributes describe the integrity constraints of the n-ary relationship and must not be infringed. They constitute a restriction for dependencies of fewer attributes. The paper formulates the rules to which fuzzy functional dependencies between (n-1) attributes of the n-ary relationship must be subordinated.