semantic faceted search with semfacet presentation
DESCRIPTION
Abstract An increasing number of applications rely on RDF, OWL 2, and SPARQL for storing and querying data. SPARQL, however, is not targeted towards end-users, and suitable query interfaces are needed. Faceted search is a prominent approach for end-user data access, and several RDF-based faceted search systems have been developed. There is, however, a lack of rigorous theoretical underpinning for faceted search in the context of RDF and OWL 2. In this paper, we provide such solid foundations. We formalise faceted interfaces for this context, identify a fragment of first-order logic capturing the underlying queries, and study the complexity of answering such queries for RDF and OWL 2 profiles. We then study interface generation and update, and devise efficiently implementable algorithms. Finally, we have implemented and tested our faceted search algorithms for scalability, with encouraging results.TRANSCRIPT
Semantic Faceted Search with SemFacet
Evgeny Kharlamov Information Systems Group Department of Computer Science University of Oxford
§ Keyword search is the paradigm to access data on the Web, company websites, etc
§ Limitations of keyword search
§ Too many docs contain keywords
§ Meaning is not built in keywords
§ Becomes the art of “finding the best combination”
§ Limited control on search
Finding Data w/ Keywords is Hard
How to Improve Search Experience?
§ Improve the search paradigm § End-user oriented query formulation interfaces
§ Faceted search
§ Improve the data model § Semantic Web models
§ Our proposal: § do both and combine
§ Faceted search § Semantic Web model
§ A facet = control mechanism § Name § Set of values
Enhancing Keyword Search with Facets
§ A facet = control mechanism § Name § Set of values
§ Facets in action § Choose a value
Enhancing Keyword Search with Facets
§ A facet = control mechanism § Name § Set of values
§ Facets in action § Choose a value § Restrict search result
§ Advantages of facets § Allow to say what you
really mean § Give control over
search
Enhancing Keyword Search with Facets
Faceted Search in the Nutshell
stars
3-stars
restaurant
§ Search over one set of items
§ Items annotated with § Strings
§ Search result: subset of items
Asian
Italian
4-stars 5-stars
French
Find 4-star hotels with French restaurants
Faceted Search in the Nutshell
stars
3-stars
restaurant
§ Search over one set of items
§ Items annotated with § Strings
§ Search result: subset of items
Asian
Italian
4-stars 5-stars
French
Find 4-star hotels with French restaurants
Faceted Search in the Nutshell
stars
3-stars
restaurant
§ Search over one set of items
§ Items annotated with § Strings
§ Search result: subset of items
Asian
Italian
4-stars 5-stars
French
Find 4-star hotels with French restaurants
Faceted Search in the Nutshell
stars
3-stars
restaurant
§ Search over one set of items
§ Items annotated with § Strings
§ Search result: subset of items
Asian
Italian
4-stars 5-stars
French
Find 4-star hotels with French restaurants
output
F-Search is the De Facto Standard
Semantic Web Models
§ RDF data model § objects annotated with strings and objects
§ OWL 2 ontologies
§ structure vocabularies of annotations
stars 4-stars French
restaurant
type walking distance to
French restaurant is a Restaurant that offers French cuisine.
FrenchRestaurant ⊑ Restaurant ⊓ ∃ offers.FrenchCuisine
Enhancing Search with SW in Practice
Enhancing Search with SW in Practice
Enhancing Search with SW in Practice
embedding semantic annotations
Hello, my name is John Doe. I study at the University if Dreams. My daughter is Alice....
<section itemscope itemtype = "http://dava-vocabulary.org/Person" itemid = "http://myitems/john-doe-1234" > Hello, my name is <span itemprop="name">John Doe</span>. I study at the <span itemprop="affiliation">University of Dreams</span> My daughter is <span itemtype = "http://dava-vocabulary.org/children" itemid = "http://myitems/alice-doe-5678" > Alice </span> ....
Semantic Web Models
§ RDF data model § objects annotated with strings and objects
§ OWL 2 ontologies
§ structure vocabularies of annotations
from 2011 to 2012 the fraction of structured data went from 3.5% to 13%
Semantic Web Models
§ RDF data model § objects annotated with strings and objects
§ OWL 2 ontologies
§ structure vocabularies of annotations
from 2011 to 2012 the fraction of structured data went from 3.5% to 13%
How to Improve Search Experience?
§ Improve the search paradigm § End-user oriented query formulation interfaces
§ Faceted Search
§ Improve the data model § Semantic Web models § RDF Data § OWL 2 ontologies
§ Our proposal: § Semantic Faceted Search that combines
§ Faceted search § Semantic Web model
4-stars
Semantic Faceted Search in the Nutshell
stars
3-stars § Search over
several sets of items
§ Items annotated with § Strings § Items
§ Search result: § user-chosen
subset of items
Asian Italian 5-stars French
Find 4-star hotels with French restaurants that are walking distance to Eiffel tower
restaurant
type
walking distance to
Semantic Faceted Search in the Nutshell
stars
3-stars § Search over
several sets of items
§ Items annotated with § Strings § Items
§ Search result: § user-chosen
subset of items
Asian Italian 4-stars 5-stars French
Find 4-star hotels with French restaurants that are walking distance to Eiffel tower
restaurant
type
walking distance to
Semantic Faceted Search in the Nutshell
stars
3-stars § Search over
several sets of items
§ Items annotated with § Strings § Items
§ Search result: § user-chosen
subset of items
Asian Italian 4-stars 5-stars French
Find 4-star hotels with French restaurants that are walking distance to Eiffel tower
restaurant
type
walking distance to
Semantic Faceted Search in the Nutshell
stars
3-stars § Search over
several sets of items
§ Items annotated with § Strings § Items
§ Search result: § user-chosen
subset of items
Asian Italian 4-stars 5-stars French
Find 4-star hotels with French restaurants that are walking distance to Eiffel tower
restaurant
type
walking distance to
Semantic Faceted Search in the Nutshell
stars
3-stars § Search over
several sets of items
§ Items annotated with § Strings § Items
§ Search result: § user-chosen
subset of items
Asian Italian 4-stars 5-stars French
Find 4-star hotels with French restaurants that are walking distance to Eiffel tower
restaurant
type
walking distance to
output
Semantic Faceted Search in the Nutshell
stars
3-stars § Search over
several sets of items
§ Items annotated with § Strings § Items
§ Search result: § user-chosen
subset of items
Asian Italian 4-stars 5-stars French
Find 4-star hotels with French restaurants that are walking distance to Eiffel tower
restaurant
type
walking distance to
output
Semantic Faceted Search in the Nutshell
stars
3-stars § Search over
several sets of items
§ Items annotated with § Strings § Items
§ Search result: § user-chosen
subset of items
Asian Italian 4-stars 5-stars French
Find 4-star hotels with French restaurants that are walking distance to Eiffel tower
restaurant
type
walking distance to
output
Research Contributions § Solid foundation for Semantic F-Search
§ Projection of ontologies on graph data structures
§ Allows to incorporate ontologies into faceted search
§ Gives better faceted interfaces § Generate more facets / Prune irrelevant facets
§ Scalable algorithms to
§ generate and update facets from § Data and Ontologies
§ Algorithms to evaluate faceted queries over semantic data § Exploits bottom up query evaluation
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Stanford Uni.
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Stanford Uni.
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Harvard Uni.Georgetown Uni.
SemFacet System § Integration of
§ Keyword search and § Semantic faceted search
§ Main features § Automatic generation of f-search interfaces
over RDF data and OWL 2 ontologies § In memory § Online and offline reasoning § Efficient on millions of triples
§ Flexible configuration
§ Interchangeable triple stores § RDFOX, PAGOdA, Hermit, Sesame
§ Configurable answers (snippets) § Support of Or and And facets
Faceted Query Interface
Answers as Snippets
PresentationLayer
ApplicationLayer
DataLayer
Facet Generator
QueryConverter
Snippet Generator
Ontology Data
Triple Store:
KBS Engine
Keyword Based Search
Inverted Index e.g. DBpedia
AbstractsRDFOX, PAGOdA, Hermit, Sesame
SemFacet Team
§ Marcelo Arenas
§ Bernardo Cuenca Grau
§ Evgeny Kharlamov
§ Sarunas Marciuska
§ Dmitriy Zheleznyakov