Standards for networked knowledge organisation systems Ron Davies European Library Automation Group Bucharest, April 2006

A critical role Future of the web depends on distributed services interoperating using semantic descriptions Future of the library depends on providing integrated access to dispersed and disparate resources Intelligent, integrated subject access needs networked knowledge organisation systems

NKOS Networked Knowledge Organisation Systems Thesauri, classification schemes, subject heading schemes, taxonomies Network-accessible to human or machine clients Available to a variety of different applications

What can an NKOS do? Support discovery (browsing) Translate a search –Natural language -> controlled vocabulary –Spoken languages (English -> French) –Indexing languages (AGROVOC -> LCSH) Enrich a search (expand, refine) Display results in a meaningful way Automatic classification /categorisation Without standards, each vocabulary means developing a new service

Levels of standards Content standards Communication (format) standards Service (protocol) standards

New content standards IFLA Guidelines for Multilingual Thesauri (2005) ANSI / NISO Guidelines for Monolingual Controlled Vocabularies Z British Standard BS 8723 Structured Vocabularies For Information Retrieval ( )

BS 8723 Structured vocabularies = Knowledge organisation systems Purpose –Update ISO and BS standards (1985) –Update from print format to networked, electronic applications –Provide guidance on electronic management and use –Integrate mono- and multi-lingual standards

Pt 1 - Definitions, symbols, abbreviations Pt 2 - Thesauri Pt 3 - Vocabularies other than thesauri Pt 4 - Interoperability between vocabularies Pt 5 - Interoperability between components of IR systems BS 8723

Equivalence Re-examine notion of equivalence –Synonyms or quasi-synonyms in a monolingual context –In a multilingual context –In mapping one vocabulary to another (classifications, filing plans, taxonomies, subject headings, ontologies)

Symmetry Traditional symmetrical multilingual thesaurus –Each concept must have an equivalent in each language --> forced meanings, loan words, coined words or neologisms Asymmetrical multilingual thesaurus –Different numbers of terms/concepts in different languages –No longer enforce one-to-one correspondence between languages BUT more complex for systems to use

bétail gros bétail boeufcheval horses cattle livestock French English

bétail gros bétail boeufcheval horses cattle livestock ? Multilingual thesaurus - Solution A

bétail gros bétail boeufcheval horses cattle livestock Multilingual thesaurus- Solution B

bétail gros bétail boeufcheval horses cattle livestock Asymmetrical thesaurus / mapping

Mapping Establishing equivalences between one structured vocabulary and another UMLS, MACS (Clavel, Landry), HILT Similar complex, partial, inexact, hierarchical equivalences Information systems will need to support these equivalences

IR system interoperability –Ability of a search/indexing system to make use of more than one KOS in a networked environment Management of structured vocabularies –Translation / adaptation –Migration From one management system to another From management system to IR application Goals for communication standards

Communication standards Tend to be vocabulary-, application- or protocol- specific –Tag/data format –ISO 2709 / MARC Authorities format –Institution-specific XML –VocML –Alexandria Digital Library Protocol –ZThes (Z39.50 Profile) –VDEX –SKOS Core (Semantic web)

Semantic Web Application Development (SWAD) Semantic web activity –EU- and W3C- sponsored research –Simple Knowledge Organisation System (SKOS) Core –Make existing KOS (thesauri, classifications, subject heading lists) usable in framework of Semantic Web –Uses Semantic Web standards = XML/RDF (not Topic Maps)

SKOS SKOS Core (version 2.0) –SKOS Core Vocabulary A set of RDF classes and properties –SKOS Core Guide Identify concepts via URI Describe concepts via RDF Publish concepts via an RDF document available from HTTP or RDF server

Simple example economic aid fr aide économique es ayuda ecónomica SN Use for aid at international level. UF economic assistance BT development aid NT financial aid RT financial grants

economic aid skos:prefLabel Class (Concept) Property Literal subject predicate object

development aid economic aid skos:prefLabel skos:broader skos:prefLabel

development aid economic aid skos:prefLabel financial aid financial grants skos:broader skos:prefLabel skos:related skos:narrower

development aid economic aid skos:prefLabel economic assistance skos:altLabel financial aid financial grants skos:broader skos:prefLabel skos:related skos:narrower Use for aid at international level. skos:scopeNote

development aid economic aid skos:prefLabel economic assistance skos:altLabel financial aid financial grants skos:broader skos:prefLabel skos:related skos:narrower Use for aid at international level. skos:scopeNote xml-lang=“en”

development aid economic aid skos:prefLabel economic assistance skos:altLabel financial aid financial grants skos:broader skos:prefLabel skos:related skos:narrower Use for aid at international level. skos:scopeNote xml-lang=“en” aide économique aide financière xml-lang=“en” skos:altLabel skos:prefLabel xml-lang=“fr”

economic aid economic assistance aide économique aide financière Use for aid at international level.

Other properties / classes skos:definition / skos:historyNote / skos:editorialNote /skos:changeNote skos:hiddenLabel skos:Collection / skos:member skos:hasTopConcept skos:ConceptScheme / skos:inScheme Properties can be extended (e.g. for specific types of BT/NT relationship or types of notes)

SKOS issues Ontology approach doesn’t allow for all thesaurus information Information about non-preferred terms Equivalences between non-preferred terms For web interoperability, not for management RDF / Topic Maps - the Betamax/VHS of subject access? Versioning / Mapping / Take up / Protocols

BS 8723 Part 5 Interoperability of structured vocabulary components of an IR system –Aims to list and evaluate different format and service approaches to thesaurus interoperability –Input from a wide number of people expert in a variety of technologies –For more information, contact Ron Davies ron (a) rondavies.be

Conclusion Most interesting time for structured vocabularies since the 1960s Urgent need for broad-based standards to facilitate network interoperability in information retrieval Important progress in standards though more work to be done

For more information IFLA Guidelines ANSI Z BS SKOS 5th European NKOS Workshop (Sept. 21, 2006)