New semantics for the membership degree in fuzzy databases

This paper proposes a definition of a fuzzy relational schema that include fuzzy integrity constraints (FIC). Unlike others approaches, we assign a degree to each tuple of the relation which measures of the compatibility between tuples and constraints defined on the relation. Among FIC, we are interested in fuzzy explicit integrity constraints (FEIC) that are not supported by the data model. To specify them, we propose an extension of an assertion language used to describe integrity constraints in relational databases. Using the possibility theory, we finally explain the method to calculate the compatibility degree within the limit of individual constraints.