Stéphane GRUMBACH

Short Biography
During the 1990s, I worked at INRIA, in the Verso project in Rocquencourt with several interruptions to go abroad. During the year 1994/1995, I went for a sabbatical in the University of Toronto, Canada. When I came back, I headed the Verso project with Sophie Cluet, while Serge Abiteboul was in Stanford. In 1996/1998, I spent two years in Italy in the University of Roma 3, and the IASI Lab of CNR. I became research director at INRIA in 1997.

In 2000, I got involved in the management of international cooperation. From 2000 to 2003, I was director for international relations at INRIA. I then became science counselor in the French Embassy in Beijing from 2003 to 2005. I joined the Sino-French IT Lab, LIAMA in Beijing, that I headed during four years 2006-2009. In 2006, I got the title of PhD supervisor of the Chinese Academy of Sciences. I am the first foreigner to obtain this title, in any field, in the Chinese Academy of Sciences. In LIAMA, I launched the Netquest research group, which develops high level programming abstractions for applications distributed over networks.

Education
I received a master in mathematics from the University of Paris VII in 1985, and a master in Chinese studies also from the University of Paris VII in 1987. I got my PhD in computer Science from the University of Paris XI in 1990 under the supervision of Serge Abiteboul. I did a postdoc in the University of California in San Diego in 1990 with Victor Vianu. In 1995, I got my habilitation thesis from the University of Paris XI.

Research Interests
Most of my scientific activity is devoted to computer science. For my activities related to China see my page on Science and Technology in China.

I am the Principal investigator of the Netquest Project team in LIAMA, and pursue research on programming models for distributed applications over networks. For more on my present interests see the project's web page.

As a researcher in the field of databases, I have worked extensively on the development and the foundations of query languages for complex data types. Query languages, unlike programming languages, offer a very limited expressive power and are extremely easy to evaluate over very large quantity of data. The general purpose of my work was to define high level query languages based on logical formalisms (such as first-order logic), which can model complex data, independently of their physical representation, and are both easy to use (for the user) and easy to evaluate (for the processor).

I have considered a large class of data types, such as complex objects, extending the relational model with nested sets, a construct fundamental in most formalisms today (eg XML), as well as bags and lists. Several of my results deal with theoretical properties of the query languages, such as their expressive power and complexity. I have shown in particular how to define tractable query languages for complex data types.

Spatio-temporal data also attracted my interest. I contributed to the development of the constraint data model which allows the representation of spatial data as infinite relations defined by numerical constraints. It can be shown that these data can be manipulated much like the finite relations of Codd model. I developed the DEDALE system, a spatial database prototype based on constraints.

Statistical data such as those produced by census bureaus raise considerable challenges as well. Interestingly Census bureaus have no means to decide which queries they can answer given the aggregate tables they detain. I have proposed a formalization of the schema of the tables to allow automatic computation of some queries. This problem is a particular instance of the problem of answering queries using views.

I got also interested in biological data, and I designed a compression algorithm for DNA sequences, BIOCOMPRESS, which to the best of my knowledge has not been surpassed.

Publications
I have written over 80 papers in international conferences and journals. The list of most of my publications can be found on the DBLP server. The files can be downloaded from the following archives: Gemo, HAL and arXiv. References to my papers can be found on the scientific literature digital library citeseer as well as on Google Scholar.

I have been general chair of the 10th Asian Computing Science Conference, ASIAN 2005, Data Management on the Web, Kunming, China, December 7-9, 2005, Springer LNCS 3818; and co-PC Chair of the 9th International Conference on Mobile Data Management (MDM'08) Beijing, China, April 27-30, 2008.

Teaching and Ph.D. students
Five students graduated under my supervision. They all have academic positions in the USA and Europe.

Zoé Lacroix Query languages, implicit definition and constraint databases; University Paris XI, June 1996; Professor Arizona State University, USA.

Fariza Tahi DNA compression and pattern discovery; University Paris XI, January 1997; Professor University Evry, France.

Luc Segoufin Topological spatial data manipulation; University Paris XI, January 1999; Researcher INRIA, France.

Leonardo Tininini Querying aggregate data; University La Sapienza, Italy, Avril 2000; Researcher IASI-CNR, Italy.

Pierangelo Veltri A view system for XML data on the web; University Paris XI, October 2002; Professor University of Calabria, Italy.