Contact.
- eMail:
- Paper mail (work):
- Department of Computer Science, Oxford University
Wolfson Building, Parks RoadOxford OX1 3QD
United Kingdom - Office:
- 351, Wolfson Building, Parks Road
- Telefon (office):
- +44-1865-6-10643
- Paper mail (home):
- Flat 8 Summertown Court
264-266 Woodstock Road
Oxford OX2 7NW
United Kingdom
Currently working on...
Implementation of Web Query Language Reconsidered: Beyond Tree and Single-Language Algebras at (Almost) No Cost
continuation of my Doctoral thesis (supervisor François Bry, reviewer Georg Gottlob), “summa cum laude”. Institute for Informatics, University of Munich.
In my thesis, I introduce a novel class of graphs (CIGs), that is a proper subclass of trees and forests, yet still exhibits linear time and space complexity for tree query evaluation. This class of graphs is complemented by a query algebra, called CIQCAG. CIQCAG evaluates any graph query on any form of graph, yet is linear for tree queries on CIGs. Read on »
RDFLog: Taming Existence in RDF Querying
Work in progress, published at WLP and RR.
We have reconsidered the combination of RDF and rules, paying particular attention to the novel features of RDF such as blank nodes or RDFS. The result, called RDFLog, illustrates (a) the cost of blank nodes for RDF querying, (b) decidable fragments of RDF-based rule languages, and (c) establishes a new normal form for RDF rules with blank nodes. A prototype for fast, XSB-based evaluation of RDF queries with (possibly recursive) rules and blank nodes in any position is available. Read on »
Quo Vadis, Web Queries?
Work in progress, published in Proc. Int'l. Workshop on Semantic Web Technology (Web4Web), 2008, and in KiWi Deliverable D2.1.
Various query languages for Web and Semantic Web data, both for practical use and as an area of research in the scientific community, have emerged in recent years. At the same time, the broad adoption of the internet where keyword search is used in many applications, e.g. search engines, has familiarized casual users with using keyword queries to retrieve information on the internet. Unlike this easy-to-use querying, traditional query languages require knowledge of the language itself as well as of the data to be queried. Keyword-based query languages for XML and RDF bridge the gap between the two, aiming at enabling simple querying of semi-structured data, which is relevant, e.g., in the context of the emerging Semantic Web. This article presents an overview of traditional query languages for XML and RDF, focused on emerging preeminent exemplars in each field, and contrasts these languages with the field of keyword querying for XML and RDF. Read on »
A bit about…
I've been working as a researcher on databases and the Semantic Web for over 6 years. In that time I've been involved
- in establishing an equivalent, forward-only normal form for XPath that is now widely cited and used;
- in the design and implementation of a streaming processor for nearly full XPath with close to time and space optimal complexity for any XPath evaluation;
- in the design and implementation of the first versatile Web query language Xcerpt that combines ease of use with the ability to access data in different Web formats;
- in the development of a linear time and space evaluation of tree queries on a substantially larger sets of graphs than covered by previous methods;
- in the design and implementation of an algebra and abstract machine common to most Web query languages such as Xcerpt, XQuery, XPath, Xcerpt, and SPARQL, that provides the best-known complexity for evaluating each of these languages.
My current focus is on the last two items, in particular on further investigation of linear time and space evaluation for a novel class of graphs, called continuous-image graphs, introduced in my doctoral thesis. Read on »
I am also interested in applications of logic and logic programming to Web information systems. We are currently investigating, with colleagues from Oxford University, the impact of existential knowledge (or blank nodes) on querying RDF with rules. We have established a normal form for rules with existential quantifiers (where no universal quantifier occurs in the scope of an existential one) and proved that this normal form is equivalent to rules where universal and existential quantifiers can arbitrarily alternate. Read on »
Curriculum vitae
- 2010–
- Senior Post-Doc in the DIADEM ERC project at the Department of Computer Science, Oxford University
- 2008–2010
- Research and teaching assistant at the University of Munich
- 2004–2008
- Research assistant in the EU network of excellence REWERSE at the University of Munich
- 2003
- Diploma in computer science with distinction at the University of Munich
- 2000–2001
- External consultant for IT-Startup Yollo AG (design and development of Web 2.0 editor for movies with ad synchronisation)
- 1996–1998
- Software engineer at the Diakonissenanstalt Stuttgart
- 1996
- High school diploma (Abitur) with distinction in computer science, history, and ancient greek at the Eberhard-Ludwigs-Gymnasium, Stuttgart
Awards, Scholarships, and Distinctions
- 2008
summa cum laude dissertation in computer science- 2003
- diploma in computer science with distinction
- 1995
- awarded scholarship by the German National Merit Foundation (“Studienstiftung des Deutschen Volkes”)
- 1995
- first place in state contest on ancient greek by Humanismus Heute
- 1995
- accepted to nation-wide summer school for intellectually gifted students (“Deutsche SchülerAkademie”) on the topic of incompleteness of formal systems supported by the german ministry for education and research and the “Stifterverband für die Deutsche Wissenschaft”
Publications.
peer-reviewed
- 2011
-
Taking the OXPath down the Deep Web
with Andrew Sellers, Georg Gottlob, Giovanni Grasso, and Christian Schallhart. In Proc. Int'l. Conf. on Extending Database Technology (EDBT). 2011. Read on »
- 2010
-
Not So Creepy Crawler: Crawling the Web with XQuery
with Franziska von dem Bussche, Klara Weiand, Benedikt Linse, and François Bry. In Proc. Future Internet Symposium (FIS), (System demonstration). 2010. Read on »
KWilt: A Semantic Patchwork for Flexible Access to Heterogeneous Knowledge
with Klara Weiand, Steffen Hausmann, and François Bry. In Proc. Int'l. Conf. on Web Reasoning and Rule Systems (RR). 2010. Read on »
A RPL through RDF: Expressive Navigation in RDF Graphs
with Harald Zauner, Benedikt Linse, Tim Furche, and François Bry. In Proc. Int'l. Conf. on Web Reasoning and Rule Systems (RR). 2010. Read on »
PEST: Term-Propagation over Wiki Structures as Eigenvector Computation
with Klara Weiand, Fabian Kneißl, and François Bry. In Proc. Workshop on Semantic Wikis (SemWiki), Best paper award. 2010. Read on »
Not So Creepy Crawler: Easy Crawler Generation with Standard XML Queries
with Franziska von dem Bussche, Klara Weiand, Benedikt Linse, and François Bry. In Proc. Int'l. World Wide Web Conf. (WWW), (System demonstration). 2010. Read on »
- 2009
-
The Perfect Match: RPL and RDF Rule Languages
with Francois Bry, Benedikt Linse. In Proc. Int'l. Conf. on Web Reasoning and Rule Systems (RR), 2009. Read on »
SPARQLog: SPARQL with Rules and Quantification
with Francois Bry, Clemens Ley, Benedikt Linse, Bruno Marnette, and Olga Poppe. In R. De Virgilio, F. Giunchiglia, and L. Tanca, editors, Semantic Web Information Management: A Model-based Perspective. Springer, 2009. Read on »
Labeling RDF Graphs for Linear Time and Space Querying
with Francois Bry and Antonius Weinzierl. In R. De Virgilio, F. Giunchiglia, and L. Tanca, editors, Semantic Web Information Management: A Model-based Perspective. Springer, 2009. Read on »
Web Queries: From a Web of Data to a Semantic Web
with Francois Bry and Klara Weiand. Tutorial at Int'l. Conf. on Web Information System Engineering (WISE). 2009. Read on »
Four Lessons in Versatility or How Query Languages Adapt to the Web
with François Bry, Benedikt Linse, Alexander Pohl, Antonius Weinzierl, and Olga Yestekhina . In F. Bry and J. Maluszynski, editors, Semantic Techniques for the Web. Springer, 2009. Read on »
Semantic Web Query Languages
with James Bailey, Francois Bry, and Sebastian Schaffert. In M. T. Özsu and L. Liu, editors, Encyclopedia of Database Systems. Springer, 2009. Read on »
- 2008
-
Quo Vadis, Web Queries?
with Klara Weiand and François Bry. In Proc. Int'l. Workshop on Semantic Web Technology (Web4Web), 2008. Read on »
XcerptRDF: A Pattern-based Answer to the Versatile Web Challenge
with François Bry and Benedikt Linse. In Proc. Workshop on (Constraint) Logic Programming (WLP), 2008. Read on »
RDFLog: It's like Datalog for RDF
with François Bry, Clemens Ley, Benedikt Linse, and Bruno Marnette. In Proc. Workshop on (Constraint) Logic Programming (WLP), 2008. Read on »
Taming Existence in RDF Querying
with François Bry, Clemens Ley, Benedikt Linse, and Bruno Marnette. In Proc. Int'l. Conf. on Web Reasoning and Rule Systems (RR) (Poster), 2008. Read on »
Simulation Subsumption or Déjà vu on the Web
with François Bry and Benedikt Linse. In Proc. Int'l. Conf. on Web Reasoning and Rule Systems (RR), 2008. Read on »
Implementation of Web Query Language Reconsidered: Beyond Tree and Single-Language Algebras at (Almost) No Cost
Doctoral thesis (supervisor François Bry, reviewer Georg Gottlob), “summa cum laude”. Institute for Informatics, University of Munich. Read on »
- 2007
-
Modular Web Queries---From Rules to Stores
with Uwe Aßmann, Sacha Berger, François Bry, Jakob Henriksson, and Jendrik Johannes. In Proc. Int'l. Workshop on Scalable Semantic Web Knowledge Base Systems (SSWS), LNCS 4806. 2007. Read on »
A Generic Module System for Web Rule Languages: Divide and Rule
with Uwe Aßmann, Sacha Berger, François Bry, Jakob Henriksson, and Paula-Lavinia Pătrânjan. In Proc. Int'l. RuleML Symp. on Rule Interchange and Applications, LNCS 4824. 2007. Read on »
Visual Languages: A Matter of Style
with Sacha Berger, François Bry, and Christoph Wieser. In Proc. Workshop on Visual Languages and Logic (VLL). 2007. Read on »
Completing Queries: Rewriting of Incomplete Web Queries under Schema Constraints
with Sacha Berger, François Bry, and Andreas J. Häusler. In Proc. Int'l. Conf. on Web Reasoning and Rule Systems (RR), LNCS 4524. 2007. Read on »
Querying the Web Reconsidered: Design Principles for Versatile Web Query Languages
with François Bry, Liviu Badea, Christoph Koch, Sebastian Schaffert, and Sacha Berger. In A. Sheth and M. D. Lytras (eds.), Semantic Web-Based Information Systems: State-of-the-Art Applications. 2007.
Foundations of Rule-Based Query Answering
with François Bry, Norbert Eisinger, Thomas Eiter, Georg Gottlob, Clemens Ley, Benedikt Linse, Reinhard Pichler, and Fang Wei. In G. Antoniou, U. Aßmann, C. Baroglio, S. Decker, N. Henze, P.-L. Pătrânjan, and R. Tolksdorf (eds.) Tutorial Lectures Int'l. Summer School ‘Reasoning Web’, LNCS 4636. 2007. Read on »
GRDDLing with Xcerpt: Learn one, get one free!
with François Bry, Alina Hang, and Benedikt Linse. In Proc. European Semantic Web Conf. (ESWC), (System demonstration). 2007. Read on »
- 2006
-
Rich Clients need Rich Interfaces: Query Languages for XML and RDF Access on the Web
with James Bailey, François Bry, Benedikt Linse, Paula-Lavinia Pătrânjan, and Sebastian Schaffert. In Proc. of German XML-Tage, (Tutorial). 2006. Read on »
The Web and Semantic Web Query Language Xcerpt
with Sacha Berger, François Bry, Benedikt Linse, and Sebastian Schaffert. In AIS SIGSEMIS and OSR Semantic Web Fact Book 2005. 2006. Read on »
Beyond XML and RDF: The Versatile Web Query Language Xcerpt
with Sacha Berger, François Bry, Benedikt Linse, and Andreas Schroeder. In Proc. Int'l. World Wide Web Conf. (WWW), (System demonstration). 2006. Read on »
Effective and Efficient Data Access in the Versatile Web Query Language Xcerpt
with Sacha Berger, François Bry, Benedikt Linse, and Andreas Schroeder. In Proc. Int'l. Workshop on Principles and Practice of Semantic Web Reasoning (PPSWR), (System demonstration), LNCS 4187. 2006. Read on »
Xcerpt and visXcerpt: Integrating Web Querying
with Sacha Berger, François Bry, and Tim Furche. In Informal Proc. ACM SIGPLAN Workshop on Programming Language Technologies for XML (Plan-X), (System demonstration). 2006. Read on »
Vorführung von Xcerpt und visXcerpt, Anfragesprachen für das Web
with Sacha Berger, François Bry, Benedikt Linse, and Andreas Schroeder. In Proc. GI-Workshop on Grundlagen von Datenbanken, (System demonstration). 2006. Read on »
Let's Mix It: Versatile Access to Web Data in Xcerpt
with François Bry, and Benedikt Linse. In Proc. of Workshop on Information Integration on the Web (IIWeb). 2006. Read on »
Data Model and Query Constructs for Versatile Web Query Languages: State-of-the-Art and Challenges for Xcerpt
with François Bry and Benedikt Linse. In Proc. Int'l. Workshop on Principles and Practice of Semantic Web Reasoning (PPSWR), LNCS 4187. 2006. Read on »
AMachoS - Abstract Machine for Xcerpt: Architecture and Principles
with François Bry and Benedikt Linse. In Proc. Int'l. Workshop on Principles and Practice of Semantic Web Reasoning (PPSWR), LNCS 4187. 2006. Read on »
Efficient Evaluation of n-ary Conjunctive Queries over Trees and Graphs
with François Bry, Benedikt Linse, and Andreas Schroeder. In Proc. ACM Int'l. Workshop on Web Information and Data Management (WIDM). 2006. Read on »
RDF Querying: Language Constructs and Evaluation Methods Compared
with Benedikt Linse, François Bry, Dimitris Plexousakis, and Georg Gottlob. In Tutorial Lectures Int'l. Summer School `Reasoning Web', LNCS 4126. 2006. Read on »
Querying the Semantic Web: A Case Study
with Loïc Royer, Benedikt Linse, Thomas Wächter, François Bry, and Michael Schroeder. In C. J. Baker and K.-H. Cheung (eds.), Revolutionizing Knowledge Discovery in the Life Sciences. 2006. Read on »
- 2005
-
Web and Semantic Web Query Languages: A Survey
with James Bailey, François Bry, and Sebastian Schaffert. In Tutorial Lectures Int'l. Summer School `Reasoning Web', LNCS 3564. 2005. Read on »
Querying the Standard and Semantic Web using Xcerpt and visXcerpt
with Sacha Berger, Fran\c{c}ois Bry, Oliver Bolzer, Sebastian Schaffert, and Christoph Wieser. In Proc. European Semantic Web Conf. (ESWC), (System demonstration). 2005. Read on »
The XML Stream Query Processor SPEX
with François Bry, Fatih Coskun, Serap Durmaz, Dan Olteanu, and Markus Spannagel. In Proc. Int'l. Conf. on Data Engineering (ICDE), (System demonstration). 2005. Read on »
Querying the Web Reconsidered: Design Principles for Versatile Web Query Languages
with François Bry, Liviu Badea, Christoph Koch, Sebastian Schaffert, and Sacha Berger. In Journal of Semantic Web and Information Systems, 1(2). 2005. Read on »
How to Query the GeneOntology
with Andreas Doms, Albert Burger, and Michael Schroeder. In Symposium on Knowledge Representation in Bioinformatics (KRBIO). 2005. Read on »
XML Perspectives on RDF Querying: Towards integrated Access to Data and Metadata on the Web
with François Bry, and Oliver Bolzer. In Proc. GI-Workshop on Grundlagen von Datenbanken. 2005. Read on »
Marriages of Convenience: Triples and Graphs, RDF and XML
with François Bry, and Oliver Bolzer. In Proc. Int'l. Workshop on Principles and Practice of Semantic Web Reasoning (PPSWR), LNCS 3703. 2005. Read on »
- 2004
-
Xcerpt and visXcerpt: Twin Query Languages for the Semantic Web
with Sacha Berger, François Bry, Oliver Bolzer, Sebastian Schaffert, and Christoph Wieser. In Proc. Int'l. Semantic Web Conf. (ISWC), (System demonstration). 2004. Read on »
Data Retrieval and Evolution on the (Semantic) Web: A Deductive Approach
with François Bry, Paula-Lavinia Pătrânjan, and Sebastian Schaffert. In Proc. Int'l. Workshop on Principles and Practice of Semantic Web Reasoning (PPSWR), LNCS 3208. 2004. Read on »
Datenströme
with François Bry, and Dan Olteanu. In Informatik Spektrum, 27(2). 2004. Read on »
An Efficient Single-Pass Query Evaluator for XML Data Streams
with Dan Olteanu, and François Bry. In Data Streams Track,Proc. ACM Symp. on Applied Computing (SAC), (System demonstration). 2004. Read on »
- 2003
-
Optimizing Multiple Queries against XML Streams
Diploma thesis (supervisor François Bry, Dan Olteanu), “1,0”. Institute for Informatics, University of Munich. Read on »
Evaluating Complex Queries against XML streams with Polynomial Combined Complexity
with Dan Olteanu, Tim Furche, and François Bry. In Proc. British National Conf. on Databases (BNCOD). 2003. Read on »
- 2002
-
XPath: Looking Forward
with Dan Olteanu, Holger Meuss, Tim Furche, and François Bry. In Proc. EDBT Workshop on XML-Based Data Management, LNCS 2490. 2002. Read on »
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Teaching.
Courses, Lectures, Exercises
- 2009
- Exercises for Markup-Sprachen und semi-strukturierte Daten, substitute lecturer
- 2008–2009
- Exercises for Übersetzerbau: Abstrakte Maschinen, substitute lecturer
- 2008
- Exercises for Informatik IV (supervision with Norbert Eisinger)
- 2006
- Graduate seminar on Data Modelling for the Semantic Web (design and supervision with Prof. F. Bry)
- 2005
- Graduate seminar on Query Languages and Visualisation for the Semantic Web (design and supervision with Prof. F. Bry)
- 2001
- Lab course on XML and E-Commerce (supervision with Dan Olteanu and Prof. F. Bry)
- 2000
- Lab course on XML and E-Commerce (design and supervision with Tim Geisler and Prof. F. Bry)
- 1997
- Industrial training at the Diakonissenanstalt Stuttgart on standard software (repeated half-day beginner and three-day advanced courses)
Supervised Diploma Theses (“Diplomarbeit”)
- 2009
- Olga Poppe, Subsumption-Based Resolution for Rule Languages with Rich Unification.
- 2008
- Antonius Weinzierl, Interval-Based Graph Representations for Efficient Web Querying.
- 2007
- Clemens Ley. RDFLog: Taming Existence—Logic-based Querying of RDF
with Existential Variables.
Hatice Serap Durmaz. An Object-oriented API for Xcerpt. - 2006
- Michael Brade. Design and Implementation of an Abstract Machine for
Single-Rule Xcerpt (AMAXOS).
Clemens Schefels. Serving Xcerpt to the Web.
Benedikt Linse. Automatic Translation Between XQuery and Xcerpt. - 2005
- Andreas Schroeder. An Algebra and Optimization Techniques for Simulation Unification.
Oliver Bolzer. Towards Data-Integration on the Semantic Web: Querying RDF with Xcerpt.
Supervised Project Theses (“Fortgeschrittenenpraktikum”)
- 2008
- Antonius Weinzierl. All-Star Compilation: From XQuery, Xcerpt to the AMachoS Algebra.
- 2007
- Liza Pullukkara. XML Data Parser for Xcerpt: Survey and Preliminary Implementation.
- 2005
- Michael Brade. Towards an Abstract Machine for Xcerpt’s Simulation Unification.
- 2002
- Sebastian Kraus. Tamino Experience Report: Advantages and Pitfalls of an XML Database Management System.
- 2001
- Tobias Kiesling. Building an XML Information System.
Other Student Theses
- 2007
- Olga Yestekhina. A Module System for Xcerpt.
Maximilian Scherr. Functions and Primitive Datatypes for Xcerpt.
Andreas Häusler. Completing Queries: Rewriting of Incomplete Web Queries Under Schema Constraints.
Alina Hang. GRDDLing with Xcerpt: Learn one, get one free!.
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Software.
- 2008
- AMaχoS: linear time and space query engine for XQuery, XPath, SPARQL, and Xcerpt. Prototypical implementation of Xcerpt 2.0.
- 2007
- RDFLog: Prototype for fast, XSB-based evaluation of RDF queries with (possibly recursive) rules and blank nodes in any position
- Xcerptware: A version of Xcerpt with modules created in collaboration with the authors of the Reuseware composition framework
- 2004
- SPEX (Streamed and Progressive Evaluation of XPath queries): nearly full-featured evaluator for XPath on streams (but: no value-based joins) with polynomial combined complexity
- 2003
- MQ-SPEX: Multi-query optimizer for SPEX that outputs networks of SPEX's streaming operators that allow the concurrent evaluation of multiple queries. Multiple optimization algorithms for problem size up to hundreds of queries.
- 2002
- Streaming Content Manager: interactive Javascript editor for composing presentations from streaming movies and ads, including fully visual placement of ad position, ad length, etc. Developed for the now-defunct Yollo AG.
Reviewing.
Evaluator for National and International Funding Agencies
- 2009
- EU Framework 7 Call 5, ICT Objective 4.3 “Intelligent Information Management”: independent expert evaluator for both consensus and hearing stage.
- 2010
-
ESWC 2010,
Ontologies and Reasoning track: 7th Extended Semantic Web Conference, Heraklion, Greece
ESWC 2010, Semantic Web in Use: 7th Extended Semantic Web Conference, Heraklion, Greece
ESWC 2010, AI Mashup Challenge 2010: 7th Extended Semantic Web Conference, Heraklion, Greece
SOFSEM 2010: 36th International Conference on Current Trends in Theory and Practice of Computer Science, Špindlerův Mlýn, Czech Republic
- 2009
-
ISWC 2009: 8th International Semantic Web Conference, Westfields Conference Center near Washington, DC, USA
WLP 2009: 23rd Workshop on (Constraint) Logic Programming, Potsdam, Germany - 2008
- Handbook of Research on Emerging Rule-Based Languages and Technologies: Open Solutions and Approaches, Information Science Reference (IGI Global)
WLP 2008: 22nd Workshop on (Constraint) Logic Programming, Dresden, Germany - 2007
- ACM WIDM 2007: 9th ACM International Workshop on Web Information and Data Management, Lisboa, Portugal
WLP 2007: 21st Workshop on (Constraint) Logic Programming, Würzburg, Germany - 2009
- Data & Knowledge Engineering: Elsevier, several reviews 2004-2010.
- 2008
- ACM CIKM 2008: 17th Conference on Information and Knowledge Management, Napa Valley, California
WISE 2008: 9th International Conference on Web Information Systems Engineering, Auckland, New Zealand
ACM PPDP 2008: 10th International ACM SIGPLAN Symposium on Principles and Practice of Declarative Programming - 2004–2007
- Reviewer for several deliverables in the EU network of excellence REWERSE