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Professor

David TomanResearch interests

Professor Toman's interests range over a variety of topics in the area of database and information systems. Of particular interest have been topics related to management of temporal and historical data in information systems. Professor Toman has focused on developing practical and theoretically sound query languages for temporal database systems as extensions of the industry standard SQL.

Professor Toman has also been developing techniques related to data expiration. These techniques form an essential component of historical data warehousing solutions. Whenever large amounts of data are repeatedly collected over a long period of time, it is necessary to have a clear approach to identifying parts of the data that are no longer needed, and a policy that allows disposing and/or archiving these parts of the data. Such policies are necessary even if adding storage to accommodate ever-growing collections of data were possible, since the growing amount of data needs to be examined during querying and in turn leads to deterioration of query performance over time. Professor Toman's research has led to the development of novel query-driven expiration techniques that use the knowledge of queries asked over the collection of data to decide which parts of the data are no longer needed. The research has also shown the limits of such techniques and their relationship to query processing in streaming systems (DSMS).

Recently, Professor Toman has been focusing on database schema languages, in particular those based on Description Logic enriched with various forms of identification constraints. The languages investigated in this line of research are tailored to enabling compilation of queries formulated over a high-level conceptual schema to code that is executed over low-level physical layouts of data, such as records and pointer structures.

Other areas of Professor Toman's expertise include topics related to temporal description logics, to using advanced data structures for efficient query processing in data warehouses (with Professor Ian Munro and in collaboration with Aruna PLC), and to query processing intrinsically ordered data models such as XML databases.

Degrees and awards

BS, MGr (Masaryk, Brno), PhD (Kansas State)

Ray Reiter Best Paper Prize (2010); Premier's Research Excellence Award, Government of Ontario (2005-2008)

Industrial and sabbatical experience

After receiving his PhD in 1996, Professor Toman was a NATO/NSERC postdoctoral fellow at the University of Toronto. He joined University of Waterloo in 1998. In 1997, 1999, and 2001 he was visiting professor at BRICS (Centre for Basic Research in Computer Science funded by the Danish National Science Foundation) at the University of Aarhus. He was visiting professor at Universita degli Studi di Roma La Sapienza and UBC in Vancouver in 2004 and 2005, respectively, and at the Faculty of Computer Science, Free University of Bozen-Bolzano in 2007-2008.

Professor Toman has served as a PC co-chair of the 12th International Symposium on Temporal Representation and Reasoning (TIME 2005) and the 2006 International Workshop on Description Logics (DL2006). He was invited to give a keynote talk on Data Expiration at the International Symposium on Temporal Representation and Reasoning Manchester UK (2002), and gave tutorials on Temporal Databases (with Jan Chomicki) at the International Conference on Advances in DB Technology, EDBT'98 in Valencia, Spain (1998), and at the International Conference on Temporal Logic, ICTL'97 in Manchester, UK (1997).

Representative publications

R. Kontchakov, C. Lutz, F. Wolter, M. Zakharyaschev and D. Toman. The Combined Approach to Query Answering in DL-Lite. Twelfth International Conference on the Principles of Knowledge Representation and Reasoning, 2010.

D. Toman and G. Weddell. Identifying Objects Over Time with Description Logics. Proceedings of International Conference on Principles of Knowledge Representation and Reasoning (KR), 2008.

A. Artale, C. Lutz, and D. Toman. Description Logic of Change. Proceedings of International Joint Conference on Artificial Intelligence, pp. 218-223, 2007.

J. Chomicki and D. Toman. Time in Database Systems. In Handbook of Temporal Reasoning in Artificial Intelligence, Fisher, Gabbay, and Vila, eds. Elsevier, pp. 429-467, 2005.

D. Toman. Logical Data Expiration. In Logics for Emerging Applications of Databases, Chomicki, van der Meyden, and Saake, eds. Springer, pp. 203-238, 2003.

D. Toman. SQL/TP a Temporal Extension of SQL. Chapter 19 in Constraint Databases, Kuper, Libkin, and Paredaens, eds. Springer, pp. 391-399, 2000.

Affiliation: 
University of Waterloo
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