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Mini-tutoriels

Cette journée des jeunes chercheurs comprend 4 mini-tutoriels par des professeurs de 4 universités belges, francophones et néerlandophones. La journée est placée sous les auspices de l'école doctorale GRASCOMP (FNRS Belgian Graduate School in Computing Science).

  • Jef Wijsen, Université de Mons-Hainaut: Database repairing and consistent query answering
  • Jan van den Bussche, Universiteit Hasselt: Towards a theory of dataspace queries
  • Jan Paredaens, Universiteit Antwerpen: Query and Transformation Languages for XML
  • Jean-Luc Hainaut, Université de Namur: Transformational database engineering


Jef Wijsen, Université de Mons-Hainaut

Jef Wijsen is professor in databases and information systems at the University of Mons (Belgium). In the last six years, he has been active in the domain of database repairing and consistent query answering. He is the author of papers in database journals (e.g., TODS) and conferences (e.g., ICDT).

Title: Database repairing and consistent query answering

Abstract: Database textbooks generally explain that integrity constraints should be satisfied at all times because they capture the set of all legal databases. Nevertheless, data inconsistency is a phenomenon that often occurs in practice. In their 1999 PODS paper, M. Arenas, L. Bertossi, and J. Chomicki propose a new paradigm for querying inconsistent databases. In their approach, a repair of an inconsistent database DB is a new database (over the same schema as DB) that is consistent and that can be obtained from DB by a minimal set of tuple insertions and deletions. In general, the same database can have multiple repairs. The consistent answer to a query then contains those tuples that are in the answer to the query on every possible repair.
In the last ten years, consistent query answering has been an active domain of research: different notions of repair have been proposed; the complexity of database repairing and consistent query answering has been studied;  techniques have been developed for computing consistent query answers.
This tutorial provides an overview of research results and open challenges in the domain of database repairing and consistent query answering.

 

Jan van den Bussche, Universiteit Hasselt

Jan Van den Bussche is professor of theoretical computer science at Hasselt University. His research is on the theory of database systems, broadly construed. He obtained his PhD from the University of Antwerp in 1993, under the supervision of Jan Paredaens. He currently serves as Chair of the ICDT Council (International Conference on Database Theory).

Title: Towards a theory of dataspace queries

Abstract: Dataspaces, invented by Franklin, Halevy and Maier, are loosely structured collections of information gathered from different sources. Querying a dataspace involves a combination of searching and navigating between objects in the dataspace. In this tutorial we first recall some basics of the theory of database queries. Then we look at first steps in extending this theory to dataspace queries.

Jan Paredaens, Universiteit Antwerpen

Jan Paredaens is a fulltime professor at the University of Antwerp, Belgium. He is the author of several books in computer science and of more than 100 scientific papers in databases. During the last three decades he investigated many domains of the database theory, such as the relational model, dependenccies and constraints, object oriented databases, and more recently semi-structured databases. He was involved in the PC and the organisation of many international conferences. He is one of the co-founders of ICDT and is at present the PODS Chair. More details on his CV can be found on http://www.adrem.ua.ac.be/~pareda//

Title: Query and Transformation Languages for XML.

Abstract: XML is a modern format that is nowadays used to store many documents, expecially on the Web. Since a set of documents can be considered as a semi-structured dataset or database, we want to query these documents. Moreover in many applications we need to transform documents in other documents, containing the same information, but with a different structure. Finally, most documents are represented in HTML  on the Web. We are going to discuss a few languages that are developed during the last decade in which we can express these queries and transformations. The most basic language is XPATH, a simple language that enables us to navigate through a document. XQUERY is a strong query language for XML and XSLT is a transformation language. These three languages are conceptually totally different. In this tutorial we will describe three elegant sublanguages, MiXPATH, MiXQUERY and MiXSLT, that contain all the characteristics of their respective superlanguage. We give their syntax and their semantics, formally and informally. We show a number of examples, indicating their different nature. Finally we present some pitfalls.


Jean-Luc Hainaut, FUNDP, Namur

Jean-Luc Hainaut is a full professor in Information System and Database Engineering at the Institute of Informatics of the University of Namur, Belgium. He has been involved in research in database engineering for more than three decades. He is a co-author of the seminal paper of the Merise method, published in 1974. He is the author of several books on Database Modelling and Database Design, and of more than 50 recent journal and conference proceedings papers. He is heading the LIBD - Laboratory of Database Applications Engineering -, a member of the PReCISE Research Center, the purpose of which is to develop general methodologies and CASE tools to assist practitioners in solving such engineering problems as database design, database reverse engineering, federated datatabases, database evolution, active databases, temporal databases, XML and web engineering. Two of the major results of his research activities, namely the DB-MAIN CASE environment and a wide spectrum database reverse engineering methodology, are distributed by ReveR, a spin-off of the LIBD.

Title: Transformational Database Engineering

Abstract: In the database engineering realm, an increasing number of bodies (e.g., OMG) and of authors recognize the merits of transformational approaches, that can produce in a systematic way correct, machine-processable and efficient database structures from abstract models. Transformations that are proved to preserve the correctness of the source specifications have been proposed in virtually all the activities related to schema engineering: schema normalization, logical design, schema integration, views derivation, schema equivalence, data conversion, reverse engineering, schema optimization, ETL, wrapper generation and others.
The proposed tutorial addresses both basic and practical aspects of database transformation techniques.  The concept of transformation is developed, together with its properties of semantics-preservation (or reversibility).  Major database engineering activities are redefined in terms of transformation techniques, and the impact on CASE technology is discussed.