Standards for networked knowledge organisation

systems

Ron Daviesron@rondavies.be

European Library Automation GroupBucharest, 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 Z39.19 - 2005

• British Standard BS 8723 Structured Vocabularies For Information Retrieval (2005-2006)

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

boeuf cheval horsescattle

livestock

French English

bétail

gros bétail

boeuf cheval horsescattle

livestock

?

Multilingual thesaurus - Solution A

bétail

gros bétail

boeuf cheval horsescattle

livestock

Multilingual thesaurus- Solution B

bétail

gros bétail

boeuf cheval horsescattle

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 économiquees ayuda ecónomicaSN Use for aid at international level.UF economic assistanceBT development aidNT financial aidRT financial grants

economic aid

skos:prefLabel

Class (Concept)

Property

Literal

subject

predicate

object

developmentaid

economic aid

skos:prefLabel

skos:broader

skos:prefLabel

developmentaid

economic aid

skos:prefLabel

financialaid

financialgrants

skos:broader

skos:prefLabel

skos:prefLabel

skos:prefLabel

skos:related

skos:narrower

developmentaid

economic aid

skos:prefLabeleconomic assistance

skos:altLabel

financialaid

financialgrants

skos:broader

skos:prefLabel

skos:prefLabel

skos:prefLabel

skos:related

skos:narrower

Use for aid at international level.

skos:scopeNote

developmentaid

economic aid

skos:prefLabeleconomic assistance

skos:altLabel

financialaid

financialgrants

skos:broader

skos:prefLabel

skos:prefLabel

skos:prefLabel

skos:related

skos:narrower

Use for aid at international level.

skos:scopeNote

xml-lang=“en”

xml-lang=“en”

xml-lang=“en”

xml-lang=“en”

xml-lang=“en”

xml-lang=“en”

developmentaid

economic aid

skos:prefLabeleconomic assistance

skos:altLabel

financialaid

financialgrants

skos:broader

skos:prefLabel

skos:prefLabel

skos:prefLabel

skos:related

skos:narrower

Use for aid at international level.

skos:scopeNote

xml-lang=“en”

xml-lang=“en”

xml-lang=“en”

xml-lang=“en”

xml-lang=“en”

aide économique

aide financièrexml-lang=“en”

skos:altLabel

skos:prefLabel

xml-lang=“fr”

xml-lang=“fr”

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:skos="http://www.w3.org/2004/02/skos/core#"><rdf:type rdf:resource="http://www.w3.org/2004/02/skos/core#Concept"/>

<skos:Concept rdf:about=" http://foobar.org/thes/7021"> <skos:prefLabel xml-lang=“en”>economic aid</skos:prefLabel> <skos:altLabel xml-lang=“en”>economic assistance</skos:altLabel> <skos:prefLabel xml-lang=“fr”>aide économique</skos:prefLabel> <skos:altLabel xml-lang=“fr”>aide financière</skos:altLabel> <skos:scopeNote xml-lang=“en”>Use for aid at international level. </skos:scopeNote> <skos:broader rdf:resource=" http://foobar.org/thes/8013" /> <skos:narrower rdf:resource=" http://foobar.org/thes/3024" /> <skos:related rdf:resource=" http://foobar.org/thes/3024" /> </skos:Concept>

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 Guidelineshttp://www.ifla.org/VII/s29/pubs/Draft-multilingualthesauri.pdf

• ANSI Z39.19http://www.niso.org/standards/standard_detail.cfm?std_id=814

• BS 8723http://www.bsonline.bsi-global.com/server/index.jsp

• SKOShttp://www.w3.org/2004/02/skos/core/

• 5th European NKOS Workshop (Sept. 21, 2006)

http://www.ukoln.ac.uk/nkos/nkos2006/