"Fully generic queries: Open problems and some partial answers", keynote talk at MEDI conference, Toulouse, 29 October 2019.
"Query languages for matrices and K-relations", given at Dagstuhl Seminar on Logics for Dependence and Independence, January 2019; also at Simon Fraser University September 2018; University of Bayreuth June 2019; NYU September 2019.
"JSON: History of a Data Model", given at Dortmund University, 20 July 2017, honoring Joachim Biskup's 70th birthday.
J-Logic: Logical Foundations of JSON Querying, PODS 2017.
Relational Database Representation and Manipulation in DNA, Konstanz Research School Chemical Biology, 26 januari 2016.
A logic-based approach to cloud computing, lecture at the EATCS Young Researchers School, Telč, Czech Republic, 1 August 2014.
Alan Turing: het Enigma, bloemlezing van de biografie van Alan Turing, seniorenuniversiteit UHasselt, 17 maart 2014.
DNAQL: A data model and query language for databases in DNA, invited talk at EDBT/ICDT 2013, Genoa, Italy, 18 March 2013.
Declarative semantics for declarative networking, 25 July 2012, KRDB Seminar at Free University of Bozen-Bolzano. Also given at meeting on Foundations of XML, Houffalize, Belgium, 23--25 April 2012.
Relative expressiveness within the calculus of relations, 14 May 2012, Meeting on Finite Model Theory, Ecole de Physique des Houches.
Temporal semantics for the Open Provenance Model, 28 February 2012, Dagstuhl Seminar on Principles of Provenance.
Towards a theory of dataspace queries invited tutorial given at the ER 2011 conference, held in Bruxelles, 31 October 2011. Also invited tutorial at the BDA conference, held in Namur, 20-22 October 2009.
A Crash Course in Database Queries is an invited tutorial given at the 26th ACM Symposium on Principles of Database Systems, held in Beijing, 11-13 June 2007.
Database Query Processing using Finite Cursor Machines given at the 11th International Conference on Database Theory, held in Barcelona, 10-12 January 2007.
Mining tree-query patterns and associations in a large graph given at the City University of Hong Kong on 21 December 2006.
The Semijoin Algebra given at the 4th International Symposium on Foundations of Information and Knowledge Systems, held in Budapest, 14-17 February 2006.
Logical aspects of spatial databases given at the Workshop on Finite and Algorithmic Model Theory, held in Durham, England, 9-13 January 2006.
Mining frequent tree-conjunctive queries in large graphs given at a symposium on Recent Trends in Relational Data Mining at the University of Leuven, 23 December 2004.
Meta-SQL: Towards practical meta-querying given at the 9th International Conference on Extending Database Technology in Heraklion, Crete, 14-18 March 2004.
Database interrogation using conjunctive queries given at the 9th International Conference on Database Theory in Siena, Italy, 8-10 January 2003.
A reformulation of the XDuce type system given at a meeting on Foundations of Semistructured Data at Schloss Dagstuhl in September 2001. (Gzipped PostScript format.)
Applications of Alfred Tarski's Ideas in Database Theory given at the Annual Conference of the European Association for Computer Science Logic, Paris, September 2001. (Gzipped PostScript format.)
Polymorphic type inference for the relational algebra given at the meeting of the FNRS Contact Group on Fundamental Computer Science at ULB, June 2001. (Gzipped PostScript format.)
From complex-object to semistructured query languages given at the Aachen-Freiburg-Mainz Seminar on Finite Model Theory in Aachen, November 2000. (Gzipped PostScript format.)
Constraint Databases given at a meeting on Finite Model Theory, Database Theory, and Computer-Aided Verification at Schloss Dagstuhl in October 1999. (Scanned-in copies of handwritten slides.)
Abstract state machines and computationally complete languages given at the ASM 2000 Workshop at Monte Verità. (Powerpoint format.)
Polynomial-space query languages given at the 2000 meeting on Finite Model Theory at CIRM. (Powerpoint format.)