skos and linked data
DESCRIPTION
Presentation at ISKO-UK Linked Data: The Future of Knowledge Organization on the Web conference. More at http://www.iskouk.org/events/linked_data_sep2010.htmTRANSCRIPT
![Page 1: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/1.jpg)
SKOS and Linked Data
Antoine Isaac
ISKO, London, Sept. 14th 2010
![Page 2: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/2.jpg)
Personal background
• Europeana• Web & Media Lab, Vrije Universiteit Amsterdam
• W3C Library Linked Data group• (2006-2009) W3C Semantic Web Deployment group
SKOS
![Page 3: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/3.jpg)
Towards a web of culture data
![Page 5: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/5.jpg)
Government data again?
![Page 6: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/6.jpg)
SKOS
Simple Knowledge Organization System
Scope: knowledge organization systems (KOS) such as thesauri, classification systems, subject heading lists…
SKOS is for representings KOSs in RDF in a simple way
![Page 7: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/7.jpg)
Representing semantics
The formal way: OWL Semantic Web ontology language
Used for ontologies that enable machine reasoning• Mother is a class• It is the intersection of the classes Woman and Parent• Parent is the class of entities of type Person that are
related to at least one other resource of type Person using the child property
…
![Page 8: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/8.jpg)
SKOS is not for formal ontologies
• Turning KOSs into ontologies is possible, but KOSs– are large– have softer “semantics”
Parent RelatedTerm Child
– have often a focus on terminological informationChild UsedFor Offspring
• Softer semantics can be useful as such for many applications!Semantic search, annotation…
![Page 9: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/9.jpg)
Basic SKOS
A set of features common to various KOS types and useful for many applications
• Concepts• Lexical properties • Semantic relations • Notes
![Page 10: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/10.jpg)
Thesaurus example
Animals
catsUF (used for) domestic catsRT (related term) wildcatsBT (broader term) animalsSN (scope note) used only for domestic cats
domestic catsUSE cats
wildcats
![Page 11: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/11.jpg)
Concepts and labels
catsUF (used for) domestic cats
skos: = http://www.w3.org/2004/02/skos/core#rdf: = http://www.w3.org/1999/02/22-rdf-syntax-ns#ex: = http://example.org/
![Page 12: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/12.jpg)
Note: multilingual labels
![Page 13: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/13.jpg)
Semantic relations
catsRT (related term) wildcatsBT (broader term) animals
![Page 14: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/14.jpg)
A SKOS graphanimalscats
UF domestic catsRT wildcatsBT animalsSN used only for domestic
catsdomestic cats
USE catswildcats
![Page 15: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/15.jpg)
SKOS mappingsSKOS allows bridging across KOSs from different contexts
KOS 1:animalscatswildcats
KOS 2:animalhumanobject
![Page 16: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/16.jpg)
Other features
• Concept groupingskos:Collection, skos:member…
• Concept documentationskos:example…
• SKOS-XL: extension for more complex representation of labels
Note: SKOS can be extended as any other RDF vocabulary
![Page 17: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/17.jpg)
Semantics for SKOS
There are some basic constraints on SKOS dataE.g., a concept has only one prefLabel per language
![Page 18: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/18.jpg)
Semantics for SKOS
There are rules to infer new factsE.g., broader and narrower are inverse of each other
![Page 19: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/19.jpg)
Semantics for SKOS
Minimal semantic commitment:• SKOS must cope with existing information and not
infer new data beyond what KOS publishers intend
![Page 20: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/20.jpg)
References
SKOS Reference http://www.w3.org/TR/skos-reference SKOS Primer http://www.w3.org/TR/skos-primer SKOS homepage http://www.w3.org/2004/02/skosSKOS wiki http://www.w3.org/2001/sw/wiki/SKOS SKOS mailing list [email protected]
![Page 21: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/21.jpg)
Benefits of SKOS?
Easily fitting KOSs into the Semantic Web & Linked Data vision
• Web-oriented representation• Re-use & sharing of concepts and their descriptions• Linking between concepts from different contexts
![Page 22: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/22.jpg)
Demo
Subject heading lists as SKOS linked data• American LCSH http://id.loc.gov• French RAMEAU: http://stitch.cs.vu.nl/rameau• German SWD: http://d-nb.info/gnd/ • mapped using manual links from the MACS project
http://macs.cenl.org
Starting from http://id.loc.gov/authorities/sh85014310#concept
![Page 23: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/23.jpg)
![Page 24: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/24.jpg)
![Page 25: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/25.jpg)
![Page 26: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/26.jpg)
![Page 27: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/27.jpg)
![Page 28: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/28.jpg)
Linked Data?
1. Use URIs as names for things2. Use HTTP URIs so that people can look up those names3. When someone looks up a URI, provide useful information
using standards (RDF, SPARQL)4. Include links to other URIs, so that they can discover more
things
Tim Berners-Lee, http://linkeddata.org/
![Page 29: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/29.jpg)
![Page 30: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/30.jpg)
![Page 31: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/31.jpg)
SKOS Implementations
Miles, Bechhofer, SKOS Implementation Report, May 19th 2009http://www.w3.org/2006/07/SWD/SKOS/reference/20090315/implementation.html
![Page 32: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/32.jpg)
Some landmark SKOS implementations
• Swedish National Library’s Libris catalogue and thesaurus http://libris.kb.se/ • Library of Congress’ vocabularies, including LCSH http://id.loc.gov/ • DNB’s Gemeinsame Normdatei (incl. SWD subject headings) http://d-nb.info/gnd/ • BnF’s RAMEAU subject headings http://stitch.cs.vu.nl/ • OCLC’s DDC classification http://dewey.info/ and VIAF http://viaf.org/ • STW economy thesaurus http://zbw.eu/stw • National Library of Hungary’s catalogue and thesauri http://oszkdk.oszk.hu/resource/DRJ/404 (example)• Wikipedia categories through Dbpedia http://dbpedia.org/ • New York Times subject headings http://data.nytimes.com/ • IVOA astronomy vocabularies http://www.ivoa.net/Documents/latest/Vocabularies.html• GEMET environmental thesaurus http://eionet.europa.eu/gemet • Agrovoc http://aims.fao.org/ • Linked Life Data http://linkedlifedata.com/ • Taxonconcept http://www.taxonconcept.org/ • UK Public sector vocabularies http://standards.esd.org.uk/ (e.g., http://id.esd.org.uk/lifeEvent/7 )
http://www.w3.org/2001/sw/wiki/SKOS/Datasets
![Page 33: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/33.jpg)
KOS Alignments?
Quite many of them are linked to some other resource• LCSH, SWD and RAMEAU interlinked through MACS mappings• GND -> DBpedia, VIAF• Libris -> LCSH• Agrovoc -> CAT, NAL, SWD, GEMET• NYT -> freebase, DBpedia, Geonames• dbPedia links are overwhelming
Hungary, STW, TaxonConcept, GND…
![Page 34: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/34.jpg)
Issues: semantic alignment of SKOS data
• In a linked data environment, the most interesting applications are the ones that cross contexts
• Mapping data between concept schemes is still scarce• More efforts are needed
Automatic or manual or a mixture of both
![Page 35: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/35.jpg)
Issues: linking KOS data to other resources
• KOSs become valuable when they bring a “semantic layer” over other resourcesE.g. books and the topics they are about
• Existing links are often only implicit in the data—using labels of concepts not their identifiers
• Semantic annotation with KOS should be a main targetCf. Drupal’s taxonomy plug-in
![Page 36: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/36.jpg)
Conclusion
Publication and linking of linked KOS data is still work in progress, but
• We are now in position of realizing the issues and working towards solving them
• We can start building applications that make use of the wealth of data already available or yet to comeMany KO resources to re-use and link to
![Page 38: SKOS and Linked Data](https://reader031.vdocuments.mx/reader031/viewer/2022020115/555067e8b4c905cc0f8b45cf/html5/thumbnails/38.jpg)
Acknowledgements
• Participants of the Semantic Web Deployment working groupAlistair Miles, Sean Bechhofer, Ed Summers, Tom Baker, Guus Schreiber…
• Library of Congress• French National Library• German National Library• MACS team (Swiss National Library)• EuropeanaConnect project