MARTINE DE CALMÈS
IRIT – Institut de Recherche en Informatique de Toulouse, Université Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse cedex, France
DIDIER DUBOIS
IRIT – Institut de Recherche en Informatique de Toulouse, Université Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse cedex, France
EYKE HULLERMEIER
Department of Mathematics and Computer Science, University of Marburg, Gemany
HENRI PRADE
IRIT – Institut de Recherche en Informatique de Toulouse, France
FLORENCE SEDES
IRIT – Institut de Recherche en Informatique de Toulouse, France

Received April 2002
Revised August 2002

Queries to a database can be made more powerful by allowing flexibility in the specification of what has to be retrieved, and by referring to cases either for expressing the request, or for computing the answer. In this paper, we present an implemented information system (applied to a database describing houses to let), based on an approach developed in the fuzzy set and possibility theory setting. This provides a unified framework for expressing users' preferences about what they are looking for, for weighting the importance of requirements, for referring to examples that they like and/or counter-examples that they dislike, and for making case-based predictions. Thus information querying goes beyond the retrieving of items from a database, and involves associated tools which help the user to figure out the actual contents of the database.

Fuzzy sets; flexible querying; querying by examples; case-based prediction