This book focuses on the recent research issues regarding the application of fuzzy set theory to extend the functionalities of database management systems.
During the past five years, the research in this field has moved from a merely theoretical framework mainly addressing the definition of fuzzy extensions of the relational database model to the consideration of other, object-oriented database paradigms, also in relation with their implementation and application in specific contexts (ex. geographic information systems), fuzzy data mining, and fuzzy functional dependencies definition.
Besides contributing to stimulate the interest in the field of fuzzy databases, the book has the aim of showing that the research carried out so far has matured some fuzzy extensions of classical databases that are feasible to be implemented and applied fruitfully in real applications.

First of all, I would like to congratulate Gabriella Pasi and Gloria Bordogna for the work they accomplished in preparing this new book in the series "Study in Fuzziness and Soft Computing". "Recent Issues on the Management of Fuzziness in Databases" is undoubtedly a token of their long-lasting and active involvement in the area of Fuzzy Information Retrieval and Fuzzy Database Systems. This book is really welcome in the area of fuzzy databases where they are not numerous although the first works at the crossroads of fuzzy sets and databases were initiated about twenty years ago by L. Zadeh. Only five books have been published since 1995, when the first volume dedicated to fuzzy databases published in the series "Study in Fuzziness and Soft Computing" edited by J. Kacprzyk and myself appeared. Going beyond books strictly speaking, let us also mention the existence of review papers that are part of a couple of handbooks related to fuzzy sets published since 1998. The area known as fuzzy databases covers a bunch of topics among which: -flexible queries addressed to regular databases, -the extension of the notion of a functional dependency, -data mining and fuzzy summarization, -querying databases containing imperfect attribute values represented thanks to possibility distributions.

Part I. Fuzzy Querying of Databases: P. Bosc, L. Duval, O. Pivert: Value-Based and Representation-Based Querying of Possibilistic Databases.- M. Nakata: Flexible Division Operators in Possibility-Based Fuzzy Relational Databases.- Part II: Data Mining Based on Fuzzy Sets: G. Chen, Q. Wei, E.E. Kerre: Fuzzy Data Mining: Discovery of Fuzzy Generalized Association Rules.- J. Kacprzyk, S. Zadrozny: On Combining Intelligent Querying and Data Mining Using Fuzzy Logic Concepts.- Part III: Geographic Information Systems Dealing with Uncertainty: M. Cobb, H. Foley, F. Petry, K. Shaw: Uncertainty in Distributed and Interoperable Spatial Information Systems.- V.B. Robinson: On Fuzzy Sets and the Management of Uncertainty in an Intelligent Geographic Information System.- A. Yazici, K. Akkaya: Conceptual Modelling of Geographic Information System Applications.- Part IV: Fuzzy Database Models: Definition and Implementation: G. de Tré, R. de Caluwe, B. Van der Cruyssen: A Generalised Object-Oriented Database-Model.- I. Blanco, J. C. Cubero, O. Pons, A. Vila: An Implementation for Fuzzy Deductive Relational Databases.- G. Bordogna, A. Leporati, D. Lucarella, G. Pasi: The Fuzzy Object-Oriented Database Management System.-