17th Italian Symposium on Advanced Database Systems

June 21st - 24th 2009, Camogli (Genova), Italy

Invited Speakers

Datalogą: A Unified Approach to Ontologies and Integrity Constraints

Georg Gottlob, Oxford University, UK

We report on a recently introduced family of expressive extensions of Datalog, called Datalogą, which is a new framework for representing ontological axioms in form of integrity constraints, and for query answering under such constraints. Datalogą is derived from Datalog by allowing existentially quantified variables in rule heads, and by enforcing suitable properties in rule bodies, to ensure decidable and efficient query answering. We first present different languages in the Datalogą family, providing tight complexity bounds for all cases but one (where we have a low complexity AC0 upper bound). We then show that such languages are general enough to capture the most common tractable ontology languages. In particular, we show that the DL-Lite family of description logics and F-Logic Lite are expressible in Datalogą. We finally show how stratified negation can be added to Datalogą while keeping ontology querying tractable in the data complexity. Datalogą is a natural and very general framework that can be successfully employed in different contexts such as data integration and exchange. This survey mainly summarizes two recent papers. This is joint work ith Andrea Calė and Thomas Lukasiewicz.

About the Speaker

Georg Gottlob is a Professor of Computing Science at Oxford University and an Adjunct Professor at TU Wien. His interests include data extraction, data exchange, algorithms for semistructured data and XML processing, database theory, algorithms for games and auctions, graph or hypergraph based algorithms for problem decomposition, knowledge representation and reasoning, complexity in ai and logic programming complexity theory finite model theory, and computational complexity. Gottlob got his Engineer and Ph.D. degrees in Computer Science from TU Vienna, Austria in 1979 and 1981, respectively. Before he moved to Oxford in 2006, he was a Full Professor of Computer Science at TU (since 1988). Before that, he was affiliated with the Italian National Research Council in Genoa, Italy, and with the Politecnico di Milano, Italy. During the spring semester 1999 he was invited McKay Professor at UC Berkeley.

Georg Gottlob was an invited speaker at many international conferences. He has received the Wittgenstein Award from the Austrian National Science Fund, is an ACM Fellow, an ECCAI Fellow, and a member of the Austrian Academy of Sciences, the German Academy of Sciences Leopoldina, and the European Academy of Sciences Academia Europaea in London. He chaired the Program Committees of IJCAI 2003 and ACM PODS 2000, was the Editor in Chief of the Journal Artificial Intelligence Communications, and is currently a member of the editorial boards of several other journals, for example CACM and JCSS.

Review of Spatial Databases and Geographic Information Systems

Hanan Samet, University of Maryland, USA

An introduction is given to the spatial database issues involved in the design of geographic information systems (GIS) from the perspective of a computer scientist. Some of the topics to be discussed include the nature of a GIS and the functionalities that are desired in such systems. Representation issues will also be reviewed. The emphasis will be on indexing methods as well as the integration of spatial and nonspatial data. Demos will be shown of the SAND Spatial Browser as well as the VASCO JAVA applet which illustrate these ideas.

About the Speaker

Hanan Samet received the B.S. degree in engineering from the University of California, Los Angeles, and the M.S. Degree in operations research and the M.S. and Ph.D. degrees in computer science from Stanford University, Stanford, CA. He is a Fellow of the IEEE, ACM, and IAPR (International Association for Pattern Recognition), and was also elected to the ACM Council in 1989-1991 where he served as the Capital Region Representative. He is the recipient of the 2009 UCGIS Research Award. He is currently a Science Foundation of Ireland (SFI) Walton Fellow at the Centre for Geocomputation at the National University of Ireland at Maynooth (NUIM).

In 1975 he joined the Computer Science Department at the University of Maryland, College Park, where he is now a Professor. He is a member of the Computer Vision Laboratory of the Center for Automation Research and also has an appointment in the University of Maryland Institute for Advanced Computer Studies. At the Computer Vision Laboratory he leads a number of research projects on the use of hierarchical data structures for geographic information systems. His research group has developed the QUILT system which is a GIS based on hierarchical spatial data structures such as quadtrees and octrees, the SAND system which integrates spatial and non-spatial data, the SAND Spatial Browser which enables browsing through a spatial database using a graphical user interface, the VASCO spatial indexing applet, and a symbolic image database system.

His research interests are data structures, computer graphics, geographic information systems, computer vision, robotics, and database management systems. He is the author of the recent book titled "Foundations of Multidimensional and Metric Data Structures" published by Morgan-Kaufmann, an imprint of Elsevier, in 2006, and of the first two books on spatial data structures titled "Design and Analysis of Spatial Data Structures", and "Applications of Spatial Data Structures: Computer Graphics, Image Processing, and GIS", both published by Addison-Wesley in 1990. He was the co-general chair of the 15th ACM International Conference on Advances in Geographic Information Systems (ACMGIS'07) and the 16th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems (ACMGIS'08). He is the founding chair of ACM SIGSPATIAL, and received best paper awards in the 2008 SIGMOD Conference, the 2008 SIGSPATIAL ACMGIS'08 Conference, and the 2007 Computers & Graphics Journal. His paper at the 2009 IEEE International Conference on Data Engineering (ICDE) was selected as one of the best papers for publication in the IEEE Transactions on Knowledge and Data Engineering.