Flexible query answering using distance-based fuzzy relations

This paper addresses the added value that is provided by using distance-based fuzzy relations in flexible query answering. To use distances and/or concepts of gradual similarity in that domain is not new. Within the last ten years, however, results in the theory of fuzzy relations have emerged that permit a smooth and pragmatic, yet expressive and effective, integration of ordinal concepts too. So this paper primarily highlights the benefits of integrating fuzzy orderings in flexible query answering systems, where the smooth interplay of fuzzy equivalence relations and fuzzy orderings allows to use simple distances as a common basis for defining both types of relations. As one case study, we discuss a pragmatic variant of a flexible query answering system-the so-called Vague Query System (VQS). The integration of fuzzy orderings into that system is provided in full detail along with the necessary methodological background and demonstrative examples.