SKOS A language to describe simple knowledge structures for the web

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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
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Supporting material

• http//wiki.usefulinc.com/UserAliman
• Links to
• Paper of this presentation
• SKOS Core Guide
• SKOS Core Vocabulary Specification
• Quick Guide to Publishing a Thesaurus

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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.

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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

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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

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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)

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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

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SKOS Development

• Open source
• Public mailing list public-esw-thes_at_w3.org
• Wiki http//esw.w3.org/topic/SkosDev
• Initial success due to community involvement

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Basic Examples

• Glossary
• Taxonomy
• Thesaurus

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Examples Note
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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.

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Glossary
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Glossary
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Glossary

• Glossary example illustrates
• Concept (class)
• definition (property)
• prefLabel (property)

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Taxonomy
From MortenFs weblog categories

• General Travelling
• Politics
• SemWeb
• RDF
• OWL

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Taxonomy
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Taxonomy
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Taxonomy

• Taxonomy example illustrates
• broader (property)
• narrower (property)

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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.

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Thesaurus
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Thesaurus

• Thesaurus example illustrates
• altLabel (property)
• scopeNote (property)
• related (property)

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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

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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

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Combining SKOS Core with
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Extensibility (1)

• Extension by combination
• Not take it or leave it
• But take what you want, create what you need

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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
  skosConcept 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

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GEMET

• E.g. GEMET
• non-standard thesaurus

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Fundamental Facets

• E.g. the AAT

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SKOS World View
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Open questions

• Relationship to RDFS/OWL ontologies
• tti ?
• Subject indicators

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SKOS web services

• Interact with large published datasource
• SPARQL query
• More specific functionality ?
• SKOS API

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WS SW ?
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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 ?