Abstract
A DB querying system is said to be flexible if it adapts to the end user expectations and expertise. This paper introduces a novel strategy to fuzzy querying that reduces the gap between complex search conditions end users have in mind and formal queries understood by the underlying DB system. In the Flexible Querying By Example paradigm, the proposed strategy, called DCQ standing for Disjunctive Concept Querying, extends a flexible querying system with subjective disjunctive concepts: it proposes two stored procedures that can be embedded in any relational database management system to build a formal query from a few user-given examples that represent the diversity of what the user is looking for. The first procedure infers the membership function of the implicit imprecise concept underlying the provided examples, with the specificity of allowing for complex disjunctive concepts: it is able to both capture properties shared by most of the selected representative tuples as well as specific properties possessed by only one specific representative tuple. The second procedure allows to exploit the resulting fuzzy concept in a query.