Preface

Nowadays, data management constitutes a blossoming domain that expands rapidly: the development of numeric applications and mobile devices generates a profusion of data in numerous activity areas. Data sources multiply at a sustained pace: social networks, sensor networks, user data, business data, web data. Data sets are getting huge, more and more open, often pervasive, and their exploitation becomes a major societal challenge. In this context, research issues are numerous and diverse, in particular those concerning access to information: customization, preference queries, data summaries, database mining, heterogeneous and complex data handling, data integration, uncertain data management. A crucial issue in database research these days is how to make systems more flexible and more human-centric. This implies, among other aspects, taking into account the preferences of the users as well as their context, to be able to deal with uncertain data, to exploit metadata such as ontologies in order to answer queries, to devise systems that exhibit a cooperative behavior, etc. Notice that similar problems arise in information retrieval as well. Besides classical database tools that need to be extended, knowledge discovery techniques can also be leveraged to make the content (and the structure) of a database more intelligible to users. The application of fuzzy set theory to the database domain is an already old story that started in the late 1970s. Indeed, it appeared very early that fuzzy sets constitute an intuitive and powerful tool to model and handle gradual concepts in the context of databases (e.g., vague predicates involved in flexible queries, approximate functional dependencies, imprecise values, user profiles). Pioneering works are those by V. Tahani, H. Prade, P. Bosc, B. Buckles and F. Petry, M. Zemankova and A. Kandel, M. Umano, J. Kacprzyk, to cite a few. Patrick Bosc played a leading role in this community from the very beginning. His position is confirmed with many publications, plenary Lectures at many prestigious conferences, but also with the response we have received while sending invitations to contribute to this volume dedicated to Patrick, to celebrate his retirement. Patrick, an expert in database theory, quickly recognized a potential of fuzzy set theory to make standard database concepts and tools closer to human way