On the Definition of Extended Norms and Co-norms to Aggregate Fuzzy Bipolar Conditions.

Abstract

Abstract — Fuzzy queries addressed to a relational database management system are based on the expression of user preferences which leads to obtain more appropriate answers. Fuzzy set theory provides powerful tools to define such conditions (fuzzy conditions). In this context, it is possible to consider fuzzy bipolar conditions which are made of two fuzzy sets to describe user's preferences: i) a fuzzy constraint to represent a mandatory requirement, ii) a fuzzy wish to represent an optional requirement. A Fuzzy constraint is mandatory in the sense that it must be fulfilled (and it can be used to discard elements). A fuzzy wish is optional since it cannot be used to discard elements (but its satisfaction brings a bonification). This paper is devoted to the aggregation of fuzzy bipolar conditions and to the definition of extended norms and co-norms.