1. Linked Open Data and federated search
Timo Gutjahr and Jwan Alhussein
07/10/2014
11/27/2018

2. Documents and Data
Linked Open Data
11/27/2018

3. Underground Data
Linked Open Data
11/27/2018

4. gapminder.org
Linked Open Data
11/27/2018

5. RULES http names Get back some data Data is relationship
Linked Open Data
11/27/2018

6. Linked Open Data
11/27/2018

7. Linked Open Data
11/27/2018

8. Linked Open Data
11/27/2018

9. Data Summaries for On-Demand Queries over Linked Data
AIFB, Karlsruhe Institute of Technology, Germany
Max-Planck Institute for Informatics, Saarbrücken, Germany
Digital Enterprise Research Institute, National University of Ireland, Galway
Ilmenau University of Technology, Ilmenau, Germany
Andreas Harth, Katja Hose, Marcel Karnstedt, Axel Polleres, Kai-Uwe Sattler, and Jürgen Umbrich
Linked Open Data
7/9/2014

10. For triple patterns this number is directly available:
● Recall, each QTree bucket stores a set of (URI,count)-pairs
● All query-relevant buckets are known after source selection
Linked Open Data
11/27/2018

11. Example - RDF Graph
Linked Open Data
11/27/2018

12. Graph as Triples
Linked Open Data
11/27/2018

13. Mathias Konrath, Thomas Gottron, Steffen Staab, Ansgar Scherp
SchemEX – Efficient Construction of a Data Catalogue by Stream-based Indexing of Linked Data
WeST – Institute for Web Science and Technologies,
University of Koblenz-Landau, Koblenz, Germany
Mathias Konrath, Thomas Gottron, Steffen Staab, Ansgar Scherp
Linked Open Data
7/9/2014

14. Linked Open Data Cloud
Every data source has a Schema but we don’t know it!
Every data source has his own SPARQL entry point.
Which data source?
Where to find resources of a type?
Linked Open Data
11/27/2018

15. Example - RDF Graph
Linked Open Data
11/27/2018

16. RDF Classes
Linked Open Data
11/27/2018

17. Example - RDF Graph
Linked Open Data
11/27/2018

18. Type Cluster
For every combination of types instances are existing an Type Cluster is created
Linked Open Data
11/27/2018

19. Example - RDF Graph
Linked Open Data
11/27/2018

20. Equivalence Classes
Linked Open Data
11/27/2018

21. Example - RDF Graph
Linked Open Data
11/27/2018

22. Index Structure
Linked Open Data
11/27/2018

23. Example: RDF graph to schema
Linked Open Data
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24. Evaluation Precision and Recall Recall 71% - 98 % Precision 74% - 100%
Linked Open Data
11/27/2018

25. Evaluation
Linked Open Data
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26. Conclusion SchemEX vs. QTree SchemEx QTree Schema-based index
Small size
Linear time complexity
QTree
Instance-based index
Ranking
Very small size
Linked Open Data
11/27/2018

27. References
Andreas Harth, Katja Hose, Marcel Karnstedt, Axel Polleres, Kai-Uwe Sattler, and Jürgen Umbrich. Data summaries for on-demand queries over linked data. In Proc. of the WWW
M. Konrath, T. Gottron, S. Staab, and A. Scherp. SchemEX – Efficient Construction of a Data Catalogue by Stream-based Indexing of Linked Data. Web Semantics: Science, Services and Agents on the World Wide Web, 16(5), 2012.
M. Konrath. SchemEX – Schema-Extraktion von Linked Open Data. Master-Arbeit, Institute for Web Science and Technologies, Universität Koblenz-Landau, FB4 Informatik
Linked Open Data
11/27/2018

28. Linked Open Data
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29. Linked Open Data
11/27/2018