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Searching Semantic Web Objects Based on Class Hierarchies


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Presentation given at LDOW2008. It describes Falcons Object Search, a keyword-based search engine for objects on the Semantic Web.

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Searching Semantic Web Objects Based on Class Hierarchies

  1. 1. Searching Semantic Web Objects Based on Class Hierarchies Gong Cheng , Weiyi Ge, Honghan Wu, Yuzhong Qu Institute of Web Science, School of Computer Science and Engineering Southeast University, Nanjing, China Presentation at the WWW 2008 Workshop: Linked Data on the Web (LDOW2008)
  2. 2. Information Islands vs. Web of Data
  3. 3. Information Islands vs. Web of Data
  4. 4. Information Islands vs. Web of Data
  5. 5. Motivation <ul><li>How to find URIs? </li></ul><ul><li>Linked Open Data brings … </li></ul><ul><li>Single-point retrieval system </li></ul>
  6. 6. Demo <ul><li> </li></ul>
  7. 7. Demo
  8. 8. Demo
  9. 9. Demo
  10. 10. Navigating Class Hierarchies for Query Restriction Filtering results Recommending subclasses
  11. 11. Combined Inverted Index <ul><li>Query: <terms, classes> </li></ul>
  12. 12. Provenance of Typing Information <ul><li>H euristics </li></ul><ul><ul><li>Dereference document </li></ul></ul><ul><ul><li>Namespace document </li></ul></ul><ul><ul><li>Documents on the same host </li></ul></ul><ul><ul><li>Other documents </li></ul></ul>
  13. 13. Class-inclusion Reasoning
  14. 14. Class-inclusion Reasoning (cont.)
  15. 15. <ul><li>Which axioms would be accepted by the reasoning engine? </li></ul><ul><ul><li>The authorized description of a vocabulary is allowed to reuse the classes from other vocabularies but CANNOT further constrain their meaning. </li></ul></ul>Class-inclusion Reasoning (cont.)
  16. 16. Recommending Subclasses <ul><li>If a subclass covers more results, it will be more likely to be recommended. </li></ul><ul><li>Algorithm </li></ul><ul><ul><li>Iterate over the first 1,000 results to collect classes. </li></ul></ul><ul><ul><li>Rank classes. </li></ul></ul><ul><ul><li>Select top K classes, s.t.: </li></ul></ul><ul><ul><ul><li>Each selected class must be a strict subclass of a current class. </li></ul></ul></ul><ul><ul><ul><li>The class inclusion relation does NOT hold between any pair of the selected classes. </li></ul></ul></ul>
  17. 17. Example <ul><li>K = 2 </li></ul>× × × Current class √ √
  18. 18. Summarizing SW Objects
  19. 19. <ul><li>Expanding textual description of SW objects </li></ul>Mapping Terms to SW Objects
  20. 20. Thank You <ul><li>Welcome to Nanjing! </li></ul>
  21. 22. Architecture
  22. 23. RDF Sentence
  23. 24. Crawler <ul><li>Seed document URLs </li></ul><ul><ul><li>PTSW, DBpedia … </li></ul></ul><ul><ul><li>Swoogle, Google … </li></ul></ul><ul><li>Parse RDF documents and dereference all the mentioned URIs. </li></ul><ul><li>… </li></ul>