On the use of fuzzy numbers in flexible querying

Abstract

An issue in extending database management functionalities is to increase the expressiveness of query languages. Flexible querying enables users to express preferences inside requirements and priorities inside compound queries. The answers are then qualified and sorted out. The fuzzy set theory offers a general framework for dealing with flexible queries. Moreover, the bag structure plays an important role in databases. Systems taking into account both flexible queries and bags introduce a new concept: fuzzy bags. A new approach of this concept, based on the notion of fuzzy cardinality, is presented in this paper. The use of fuzzy bags and fuzzy cardinalities in flexible querying is also introduced.