The growing number of datasets published on the Web as linked data brings both opportunities for high data availability and challenges inherent to querying data in a semantically heterogeneous and distributed environment. Approaches used for querying siloed databases fail at Web-scale because users don't have an a priori understanding of all the available datasets. This article investigates the main challenges in constructing a query and search solution for linked data and analyzes existing approaches and trends. Full article: http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6051410&tag=1

1. Digital Enterprise Research Institute www.deri.ie
Querying Heterogeneous Datasets on
the Linked Data Web:
Challenges, Approaches, and Trends
André Freitas, Edward Curry, João G. Oliveira,
Seán O’Riain
 Copyright 2009 Digital Enterprise Research Institute. All rights reserved.

2. IEEE Internet Computing
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3. Digital Enterprise Research Institute www.deri.ie
http://ieeexplore.ieee.org/xpls/abs_all.js
p?arnumber= 6051410&tag= 1

4. Digital Enterprise Research Institute www.deri.ie
Challenges

5. Current Scenario/Ideal Scenario
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6. Expressivity- usability trade- off
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7. Challenges
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 This analysis focuses on the investigation of
existing approaches under the perspective
of the usability-expressivity trade-off.
 This focus guides the categorization and
analysis of existing challenges, approaches
and trends.

8. Challenge Dimensions
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 Query expressivity
 Usability
 Vocabulary-level semantic matching
 Entity Reconciliation
 Semantic Tractability mechanisms

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Approaches

10. Approaches
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 Information Retrieval approaches
 Entity-centric search
 Structure search
 Natural Language approaches
 Question Answering
 Semantic best-effort natural language interfaces

11. Entity- Centric Search
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e.g. Sindice

12. Structure Search
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e.g. Semplore

13. Question Answering
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e.g. FreyA

14. Semantic Best- Effort/NL
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e.g. Treo

15. Comparative Analysis (Approaches)
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16. Digital Enterprise Research Institute www.deri.ie
Trends

17. Addressing the Challenges
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 The functionality analysis of existing
approaches provides insights on how the
major challenges should be addressed.
 This set of strategic functionalities define
the set of trends.

18. Linked Data Web
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19. Trends
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 Complementary Search and Query Services
 User Interaction and Feedback Mechanisms
 Semantic Best-Effort Query Model
 Natural Language Processing Techniques
 Distributional Semantic Model
 External Knowledge Sources for Semantic
Enrichment
 Integrated Entity Reconciliation Techniques

20. IEEE Internet Computing
Digital Enterprise Research Institute www.deri.ie

21. Digital Enterprise Research Institute www.deri.ie
http://ieeexplore.ieee.org/xpls/abs_all.js
p?arnumber= 6051410&tag= 1

22. Digital Enterprise Research Institute www.deri.ie
http://andrefreitas.org