Storing and manipulating data in distributed graphs: RDF ...
Keyword Search over RDF Graphs
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Keyword Search over RDF Graphs
Shady Elbassuoni* and Roi Blanco**
* Max-Planck Institute for Informatics
** Yahoo! Research, Barcelona
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RDF Datasets
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
Traffic hasWonPrize Academy_AwardInnerspace hasWonPrize Academy_AwardInnerspace hasGenre ComedyJoe_Dante directed InnerspaceToy_Story hasWonPrize Academy_AwardRoad_Trip hasGenre ComedyToy_Story hasGenre ComedyTom_Hanks actedIn Toy_StoryDiner hasWonPrize Academy_AwardDiner type Comedy_filmsSteve_Guttenberg actedIn DinerThe_Pink_Panther type Criminal_comedy_filmsThe_Pink_Panther hasWonPrize Academy_AwardPolice_Academy type Comedy_filmsSteve_Guttenberg actedIn Police_AcademyThe_Darwin_Awards type Comedy_films
subject predicate object
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Searching RDF Data
Structured triple-pattern queries (SPARQL) Example: comedies that have won an
academy award
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
SELECT ?mWHERE {?m hasGenre Comedy . ?m hasWonPrize Academy_Award}
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Searching RDF Data
Triple-pattern queries are very expressive but are not that useable Most users/ Search APIs prefer keyword queries
Support keyword search over RDF graphs
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
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Keyword Search over RDF Data
How to process keyword queries? Translate keyword queries into SPARQL Directly process the queries over the RDF graph
What are the results to a keyword query? Resources Triples Tuples of triples (subgraphs)
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
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Keyword Search over RDF Data
How to process keyword queries? Translate keyword queries into SPARQL Directly process the queries over the RDF graph
What are the results to a keyword query? Resources Triples Tuples of triples (subgraphs)
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
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How to process keyword queries? Translate keyword queries into SPARQL Directly process the queries over the RDF graph
What are the results to a keyword query? Resources Triples Tuples of triples (subgraphs)
Keyword Search over RDF Data
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
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How to process keyword queries? Translate keyword queries into SPARQL Directly process the queries over the RDF graph
What are the results to a keyword query? Resources Triples Tuples of triples (subgraphs)
Keyword Search over RDF Data
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
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Processing Keyword Queries
Construct a document D(t) for each triple t D(t) contains all literals in t and any text
associated with the URIs in t
Example:
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
innerspace USA1987 science fiction comedy film Joe Dante Michael Finnell Dennis Quaid Martin Short Meg Ryan academy award best visual effects …
innerspace USA1987 science fiction comedy film Joe Dante Michael Finnell Dennis Quaid Martin Short Meg Ryan academy award best visual effects …
t: Innerspace hasGenre Comedy
We can now create triple-term indexes
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Retrieving Query Results For each query keyword, retrieve a list of triples Join the triples from different lists based on their URIs
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
comedy award
Innerspace hasGenre ComedyRoad_Trip hasGenre ComedyToy_Story hasGenre ComedyDiner type Comedy_filmsPolice_Academy type Comedy_filmsThe_Darwin_Awards type Comedy_films...
Traffic hasWonPrize Academy_AwardInnerspace hasWonPrize Academy_AwardToy_Story hasWonPrize Academy_AwardDiner hasWonPrize Academy_AwardThe_Darwin_Awards type Comedy_films...
`
T: Innerspace hasGenre Comedy . Innerspace hasWonPrize Academy_Award
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Retrieving Query Results Retrieve a list of triples matching a query keyword Join the triples from different lists based on their URIs
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
comedy award
Innerspace hasGenre ComedyRoad_Trip hasGenre ComedyToy_Story hasGenre ComedyDiner type Comedy_filmsPolice_Academy type Comedy_filmsThe_Darwin_Awards type Comedy_films...
Traffic hasWonPrize Academy_AwardInnerspace hasWonPrize Academy_AwardToy_Story hasWonPrize Academy_AwardDiner hasWonPrize Academy_AwardThe_Darwin_Awards type Comedy_films...
`
T: Innerspace hasGenre Comedy . Innerspace hasWonPrize Academy_AwardT: Toy_Story hasGenre Comedy . Toy_Story hasWonPrize Academy_Award
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Retrieving Query Results Retrieve a list of triples matching a query keyword Join the triples from different lists based on their URIs
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
comedy award
Innerspace hasGenre ComedyRoad_Trip hasGenre ComedyToy_Story hasGenre ComedyDiner type Comedy_filmsPolice_Academy type Comedy_filmsThe_Darwin_Awards type Comedy_films...
Traffic hasWonPrize Academy_AwardInnerspace hasWonPrize Academy_AwardToy_Story hasWonPrize Academy_AwardDiner hasWonPrize Academy_AwardThe_Darwin_Awards type Comedy_films...
`
T: Innerspace hasGenre Comedy . Innerspace hasWonPrize Academy_AwardT: Toy_Story hasGenre Comedy . Toy_Story hasWonPrize Academy_AwardT: Police_Academy type Comedy_Films . The_Darwin_Awards type Comedy_Films
Result Ranking is crucial!!
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Language Models for Triples
D(t)
t:Innerspace hasGenre Comedy
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
w P(w|D(t))
innerspace 0.234
1987 0.123
science 0.012
fiction 0.020
comedy 0.111
film 0.179
classic 0.111
meg 0.019
ryan 0.019
oscar 0.148
. . . . . .
Esitmate from
w
P(w)
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Ranking Model
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
comedy award
T: Innerspace hasGenre Comedy . Innerspace hasWonPrize Academy_Award
but we treat triples as bags of words!
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Ranking Model
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
comedy award
T: Innerspace hasGenre Comedy . Innerspace hasWonPrize Academy_Award
probability of the structure of triple t being relevant to keyword w
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Estimating Structural Relevance
For each keyword, construct a probability distribution over predicates
Example: award
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
r P(r|w)
hasWonPrize 0.459
wasNominatedFor 0.387
type 0.112
directed 0.020
actedIn 0.021
producedIn 0.025
bornIn 0.008
. . . . . .
P(Innerspace hasWonPrize Academy_Award|award) = P(hasWonPrize|award)
estimated from the whole dataset
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Example Ranked Query Results
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
comedy award
Bag of Words
Combat_Academy type Comedy_films . The_Darwin_Awards type Comedy_filmsPolice_Academy type Comedy_films . The_Darwin_Awards type Comedy_films Innerspace hasGenre Comedy . Innerspace hasWonPrize Academy_Award
Structure Aware
Innerspace hasGenre Comedy . Innerspace hasWonPrize Academy_AwardToy_Story hasGenre Comedy . Toy_Story hasWonPrize Academy_AwardShrek hasWonPrize Academy_Award_Best_Animated_Feature . Shrek hasGenre Comedy
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Experimental Setup
User study over two RDF datasets: movies from IMDB books from LibraryThing
Models compared: Structure Aware Approach Bag of Words Approach Language-model-based Object Retrieval BANKS (keyword search over databases)
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
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Experimental Setup
30 evaluation queries Gathered relevance assessments for the top-
50 results retrieved by each model
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
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Experimental Results
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
P-value < 0.05
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Conclusion
Keyword Search over RDF data is crucial To support keyword search over RDF data
Combine structured triples with text Construct a document for each triple
Retrieve meaningful query results Tuples of joined triples Can be extended to larger subgraphs of the RDF
graph Rank the retrieved results
A language model approach that uses both text and structure
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
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Ranking Model
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011
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RDF Graphs
Shady Elbassuoni, Keyword Search over RDF Graphs, CIKM 2011