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SKOS A language to describe simple knowledge structures for the web

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  1. SKOSA language to describe simple knowledge structures for the web Semantic Web Best Practices and Deployment Alistair Miles, CCLRCBrian Matthews, CCLRCDave Beckett, ILRTDan Brickley, W3CMichael Wilson, CCLRCNikki Rogers, ILRT

  2. Supporting material http://wiki.usefulinc.com/User:Aliman Links to … • Paper of this presentation • SKOS Core Guide • SKOS Core Vocabulary Specification • Quick Guide to Publishing a Thesaurus

  3. Purpose of this talk Introduce ‘SKOS Core’ and … … find out what you think. N.B. SKOS Core recently published as W3C first public working draft … … so this is a work in progress.

  4. Context • Textual content-based web search engines are limited • Meaningful metadata can improve information retrieval & management • Metadata requires shared ‘vocabularies’ of concepts • E.g. AAT, DDC • E.g. DMOZ, Topic Exchange • To support exchange, re-use, need a simple language for expressing ‘vocabularies’ of concepts in machine-understandable way

  5. SKOS Core • ‘Simple Knowledge Organisation System’ • SKOS Core … • Tool for publishing descriptions of concepts, simple knowledge structures • Application of RDF • Cf. OWL … • OWL is a sledge hammer • SKOS Core is a nut cracker • In fact complement each other, can be used in combination to optimise cost/benefit ratio

  6. Background • Libraries use classification schemes, thesauri, subject headings, taxonomies etc. • ISO 2788-1986, ISO 5964-1985 • DESIRE project • RDF schema for thesauri • LIMBER project • RDF Thesaurus Interchange Format (TIF)

  7. Background • SWAD-Europe (EU IST 5FP) • Simple Knowledge Organisation System (SKOS) • Rename from TIF to SKOS … • Extend scope • Not just interchange • RDF is not a file format, but a formalism for distributed data management • W3C SWBPD-WG • Manages SKOS Core • Public Working Drafts (10 May 2005) • SKOS Core Guide • SKOS Core Vocabulary Specification • Quick Guide to Publishing a Thesaurus on the Semantic Web

  8. SKOS Development • ‘Open source’ • Public mailing list public-esw-thes@w3.org • Wiki http://esw.w3.org/topic/SkosDev • Initial success due to community involvement

  9. Basic Examples • Glossary • Taxonomy • Thesaurus

  10. Examples Note

  11. Glossary From RDF Semantics Glossary: Assertion (i) Any expression which is claimed to be true. (ii) The act of claiming something to be true. Class A general concept, category or classification. Something used primarily to classify or categorize other things. Resource (i) An entity; anything in the universe. (ii) As a class name: the class of everything; the most inclusive category possible.

  12. Glossary

  13. Glossary

  14. Glossary • Glossary example illustrates … • Concept (class) • definition (property) • prefLabel (property)

  15. Taxonomy General Travelling Politics SemWeb RDF OWL From MortenF’s weblog categories …

  16. Taxonomy

  17. Taxonomy

  18. Taxonomy • Taxonomy example illustrates … • broader (property) • narrower (property)

  19. Thesaurus From UK Archival Thesaurus … Term: Economic cooperation Used For: Economic co-operation Broader terms: Economic policy Narrower terms: Economic integration, European economic cooperation, European industrial cooperation, Industrial cooperation Related terms: Interdependence Scope Note: Includes cooperative measures in banking, trade, industry etc., between and among countries.

  20. Thesaurus

  21. Thesaurus • Thesaurus example illustrates … • altLabel (property) • scopeNote (property) • related (property)

  22. SKOS Core Overview • Basic description • Concept, ConceptScheme, inScheme, hasTopConcept • Labelling • prefLabel, altLabel, hiddenLabel, prefSymbol, altSymbol … (audio labels?) • Documentation • definition, scopeNote, changeNote, historyNote, editorialNote, publicNote, privateNote • Semantic relations • broader, narrower, related • Subject indexing • subject, isSubjectOf, primarySubject, isPrimarySubjectOf • Grouping • Collection, OrderedCollection, CollectableProperty, member, memberList

  23. SWED Portal • Application of SKOS Core for faceted browsing • SKOS Core used to describe relevant concepts shared by community • Environmental organisations publish description of themselves (metadata) • Portal aggregates metadata

  24. Combining SKOS Core with …

  25. Extensibility (1) • ‘Extension’ by combination • Not ‘take it or leave it’ … • But ‘take what you want, create what you need’

  26. Extension (2) • Extension by refinement • E.g. SWED areas of operation … • Define refinements (sub-properties) of SKOS Core semantic relation properties • E.g. AAT fundamental facets • Define refinements (sub-classes) of the skos:Concept class • When using ‘extension by refinements’ each class or property of SKOS Core is an ‘extension point’, with extensions guaranteed to be backwards compatible by RDFS inference

  27. GEMET • E.g. GEMET • ‘non-standard’ thesaurus

  28. Fundamental Facets • E.g. the AAT …

  29. SKOS World View

  30. Open questions … • Relationship to RDFS/OWL ontologies … • tti … ? • ‘Subject indicators’ …

  31. SKOS & web services • Interact with large published datasource … • SPARQL query … • More specific functionality … ? • SKOS API

  32. WS & SW … ?

  33. Summary • SKOS Core simple RDF language for describing and publishing ‘vocabularies’ of concepts on the (semantic) web • Glossaries, taxonomies, thesauri … • Extensible, flexible • Application e.g. SWED, GEMET • WS API ?