Given at DERI Galway on 2010/02/12. More and more data is being published on the Web through RDF; in particular – and largely under the auspices of the pragmatic Linked Data community – more and more structured data is being published within a plethora of different domains: e.g., information is being published from Wikipedia, BBC, LastFM, the UK government, etc., describing people, organisations, online communities, movies, proteins, and so forth. In this talk, I will present research I have carried out during my PhD which aims at enhancing large-scale RDF web datasets for query-answering: I will show some simple examples of problems with query-answering over the “native” RDF data, and discuss pragmatic solutions – in light of these examples – which involve using a scalable and best-effort reasoning approach. I will also discuss open questions and future directions along the lines of the above topic.

1. Enhancing Large-Scale RDF Web Knowledge-bases for Query Answering Mini-Viva Aidan Hogan 12 th February, 2010

2. Overview Fig 1: RDF Web Dataset explicit data implicit data Topic of today’s talk: How to exploit implicit data for “query answering”

4. Problem: Synonymous Omissions ex:Aidan ex:presented ex:RR2009Talk . deri:Aidan ex:presented deri:FridayTalk . Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . IMPLICT EXPLICIT

5. Problem: Synonymous Duplicates ex:Aidan ex:presented deri:FridayTalk . ex:Aidan ex:presented ex:FridayTalk . Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . IMPLICT EXPLICIT

6. Problem: Incomplete Answers ex:RR2009Talk ex:presentedBy ex:Aidan . Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . IMPLICT EXPLICIT

7. Solution: Publish Complete Data? Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . IMPLICT EXPLICIT ex:RR2009Talk ex:presentedBy ex:Aidan . ex:Aidan ex:presented ex:RR2009Talk .

8. Solution: Write Query in many ways? ex:RR2009Talk ex:presentedBy ex:Aidan . Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . ?talk ex:presentedBy ex:Aidan . IMPLICT EXPLICIT

9. Solution: Exploit OWL and RDFS… deri:Aidan ex:presented deri:FridayTalk . deri:Aidan owl:sameAs ex:Aidan . ex:RR2009Talk ex:presentedBy ex:Aidan . ex:presentedBy owl:inverseOf ex:presented . ex:Aidan ex:presented deri:FridayTalk . ex:Aidan ex:presented ex:RR2009Talk . Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . IMPLICT EXPLICIT

12. Reasoning: Make Explicit the Implicit deri:Aidan ex:presented deri:FridayTalk . deri:Aidan owl:sameAs ex:Aidan . ex:RR2009Talk ex:presentedBy ex:Aidan . ex:presentedBy owl:inverseOf ex:presented . Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . ex:Aidan ex:presented deri:FridayTalk . ex:Aidan ex:presented ex:RR2009Talk . IMPLICT EXPLICIT

17. The Web… …forecast is for muck

31. … and back again ex:RR2009Talk ex:presentedBy ex:Aidan . ex:presentedBy owl:inverseOf ex:presented . Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . IMPLICT EXPLICIT ex:Aidan ex:presented ex:RR2009Talk .

32. … but what about… ex:Aidan ex:presented ex:RR2009Talk . deri:Aidan ex:presented deri:FridayTalk . Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . IMPLICT EXPLICIT

33. … and… ex:Aidan ex:presented deri:FridayTalk . ex:Aidan ex:presented ex:FridayTalk . Query: Give me all talks presented by Aidan ex:Aidan ex:presented ?talk . IMPLICT EXPLICIT

37. 1. Web data is messy 2. Reasoning over Web data is difficult 3. Need incomplete, albeit inclusive reasoning 4. Rule execution optimisations possible through special treatment of terminological data 5. Need to consider the provenance of data 6. OWL 2 RL not immediately suitable to application over Web data 7. Incomplete OWL 2 RL support can be offered using existing technologies, in a scalable and tolerant way 8. Busy year ahead Conclusion