Abstract
In this paper, we propose an approach to query a database where the user preferences can be bipolar (i.e., express both constraints and wishes about the desired result) and the data stored in the database can be uncertain. Query results are then completely ordered with respect to these bipolar preferences, giving priority to constraints over wishes. Furthermore, we consider user preferences expressed on a domain of values which is not "flat", but contains values that are more specific than others according to the "kind of" relation. These preferences are represented by specific fuzzy sets, called "Hierarchical Fuzzy Sets" and defined over a simple ontology.We propose a use of "Hierarchical Fuzzy Sets" for query enlargement purposes. The approach is illustrated on a real-world problem concerning the selection of optimal packaging material for fresh fruits and vegetables. Patrice