Picture of Olaf Hartig Olaf Hartig
Assistant Professor (Universitetslektor)
Division for Database and Information Techniques
Department of Computer and Information Science (IDA)
Linköping University

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News

September 13, 2018: We have won the best paper award for our paper titled "CostFed: Cost-Based Query Optimization for SPARQL Endpoint Federation" at the SEMANTiCS Conference 2018. This is joint work with Muhammad Saleem, Alexander Potocki, Tommaso Soru (all University of Leipzig) and Axel-Cyrille Ngonga Ngomo (University of Paderborn). We have made available a PDF file preprint of this paper.

August 8, 2018: I published a PDF file lightweight high-level summary of our research paper about the "Semantics and Complexity of GraphQL" (PDF file preprint).

July 2, 2018: My talk about "Fundamental Properties of the GraphQL Language" at GraphQL Europe 2018 has been videotaped. You can find the recording at Youtube.

May 23, 2018: I will have the honor to serve as a research track co-chair of the 18th International Semantic Web Conference, ISWC 2019, which will take place in Auckland at the end of October 2019. Additionally, I will serve as a co-chair of the posters and demos track of the 16th European Semantic Web Conference, ESWC 2019.

May 3, 2018: I have made available a PDF file preprint of our IJCAI 2018 paper titled "A Model of Distributed Query Computation in Client-Server Scenarios on the Semantic Web." Note that this paper is an abridged version of our ISWC 2017 best research paper (preprint), which has been invited to the Sister Conference Best-Paper Track at the 27th International Joint Conference on Artificial Intelligence (IJCAI). The conference will take place in July in Stockholm.

May 2, 2018: My proposal to talk at the GraphQL Europe 2018 has been accepted. I am very excited about this opportunity to present our recent GraphQL research paper to the GraphQL community. My talk will be titled "Fundamental Properties of the GraphQL Language."

Apr. 30, 2018: I have been invited to a NII Shonan Meeting with the title "Graph Database Systems: Bridging Theory, Practice, and Engineering". NII Shonan Meetings are similar to Dagstuhl seminars. So, it is an honor to be invited, and I am very much looking forward to the event.

Apr. 17, 2018: Next week, I will attend The Web Conference (27th International World Wide Web Conference - WWW 2018) in Lyon, France. Together with Jorge Pérez (from the Universidad de Chile) we have a research paper in the main track of the conference. The title of the paper is "Semantics and Complexity of GraphQL" and we have made available a PDF file preprint of this paper. In addition to this paper, I have been invited to give a talk in the Web Stream Processing workshop at the conference. I will talk about the RDF*/SPARQL* Approach to Statement-Level Metadata in RDF. Further contributions to the conference will be a participation in a panel discussion at the Linked Data on the Web workshop (LDOW) and the chairing of a session in the main conference.

Apr. 6, 2018: A short summary paper about our ISWC 2017 best research paper has been accepted for presentation at the 12th Alberto Mendelzon International Workshop on Foundation of Databases and the Web (AMW), which will take place in May in Cali, Colombia.

Mar. 18, 2018: I have been co-author of two entries in the Encyclopedia of Big Data Technologies, and I have made available preprints of the entries now:

Research Interests

I am interested in problems related to the management of data and databases. My focus in this broad context is on data on the Web (Semantic Web and Linked Data, in particular) and on graph data, as well as on problems in which the data is distributed over multiple, autonomous and/or heterogeneous sources (keyword: federated data management). Other keywords that appear in some of my work are data provenance and data quality. Regarding all of these topics, my interests range from systems-building related research (e.g., efficient storage of datasets and databases, query processing, and query optimization) all the way to theoretical foundations (e.g., complexity and expressive power of query languages).

CV

Here is my academic CV: PDF file

Selected Publications

This following list contains selected publications. There is also a complete list of all my publications.

Program Committees

Additional Activities

Teaching

Ongoing and upcoming courses at LiU for which I am the course leader:

Earlier courses at LiU for which I was the course leader:

Other courses at LiU that I am or was involved in:

Earlier courses at UWaterloo for which I was the course leader:

Earlier practicals and seminars at HU Berlin for which I was responsible as a teaching assistant: