OCLC/ISKO-NA Preconference 5 August 2008 Michael Panzer Global Product Manager, Taxonomy Services OCLC DDC, SKOS, and Linked Data on the Web

Overview 1.Why transform the DDC into a SKOS vocabulary? 2.Creating URIs 1.What is a concept? 2.What is an information resource? 3.Analyzing DDC for modeling in RDF/SKOS 1.Identifying concepts 2.Aligning DDC elements with SKOS classes and properties 3.Modeling sematic relationships 4.Integration into RESTful web services (if we have time)

Why transform the DDC into a SKOS vocabulary? -Participation in data web is crucial for knowledge discovery tools -SKOS as publication format -Enabling data interoperability -Extensible, but dumbing down possible -Hospitability for terminologies; agile publication possible as soon as recommendation status is reached -Broadening the base of Dewey use cases and users -Rethinking access to KOS in general Caution: Most research problems of semantic integration or vocabulary construction neither solved nor touched by SKOS!

[Checklist: Webification of KOS] (Infra-)Structural choke points 1.Design of identifiers 2.Design of verbal designators (verbal plane) 3.Data representation 4.Vocabulary enhancement 5.User contribution 6.Versioning 7.Vocabulary registries

Cool URIs for the DDC (lightning overview) -Approaches to URI design -Encoding resource metadata into URIs? -Axiom of URI opacity -Genericity of resources -Dimensions of variance: time, language, format -Framing of concept instantiation -Role of Dewey classes for URIs -Classes as center of identification for DDC concepts -Information resources vs. non-information resources in web architecture

Example URIs -Generic URI - -Specific time Specific time & language - -Specific time, language & format -

Example URIs -Concept vs. representation URIs Caveat: template still might change syntactically, e.g. - -Is the identifier strategy sound? -Application to SKOS

Analyzing DDC for modeling in RDF/SKOS What to include? What makes sense as Linked Data? -DDC is fairly complex: -Manual, external and internal tables, schedules, Relative Index, … -Regular, optional numbers; number spans, centered entries, … -Elaborate note structure -Singled out as skos:Concepts right now: -Listed schedule numbers (including built numbers) -Number spans -Centered entries -Relative Index terms (in different namespace)

Analyzing DDC for modeling in RDF/SKOS Education for specific objectives Vocational education Parents--vocational education Vocational education--Great Britain Vocational education--United States Career development Career education Education of employees Employee development Human resource development … Career education Career education--United States Career education--United States--Curricula Core competencies … Vocational education Vocational training centers Relative Index Mapped LCSH skos:relatedMatch

Analyzing DDC for modeling in RDF/SKOS Vocational education Class here career education, occupational training, vocational schools Class on-the-job training, vocational training provided by industry in For vocational education at secondary level, see ; for adult vocational education, see See also for choice of vocation; also for vocational guidance in schools skos:notation skos:prefLabel skos:related

RDF model: Class (1) a skos:Concept ; skos:inScheme ; dct:created " T00:00: :00"^^ ; dct:updated " T00:00: :00"^^ ; skos:notation " "^^ ; skos:prefLabel "Vocational ; skos:broader ; skos:narrower,, ; skos:related,,.

RDF model: Class (2) skos:relatedMatch,.

RDF model: Class (3) ddc:hasIndexTerm,,.

RDF model: Class ddc:hasIndexTerm rdfs:subPropertyOf skos:relatedMatch. ddc:isIndexTermOf rdfs:subPropertyOf skos:relatedMatch ; owl:inverseOf ddc:hasIndexTerm. Extending SKOS

RDF model: Relative Index Terms Job training

RDF model: Gathering assertions about a resource

Modeling concept history events -Tracking and exposing change processes for discovery -Two recent positions: -Tennis: Augmenting SKOS with generic skos:ConceptInstance to indicate version- and vocabulary-specific skos:Concepts -Voss: Pragmatic approach focusing on retrieval; linking versions with skos:mappingRelation

Modeling concept history events -Some problems -Change on concept level Labels, relations, etc. Change on scheme (inter-concept) level Exhaustive change of concepts Complex relocation/discontinuation, splitting of concept (1-to-many) Simple relocation/discontinuation (1-to-1) Partial change of concepts Melding of a concept (integrating new topics, many-to-1) Extensive revisions (many-to-many)

Simple relocation/discontinuation T00:00: : T00:00: :00 370[.19] Psychological principles

Simple relocation/discontinuation -Two different representations of concept history modeled by skos:historyNote -Some problems: unclear semantics, unclear relationships of replacing concepts (succession, coordination?)

DDC in SKOS: Further Issues -Non-assignable concepts (node labels): skos:Collection and skos:member not usable -SKOS somewhat underspecified as RDF vocabulary; much has to be done by following best practice recommendations -SKOS tool stack still rather thin; could change after W3C draft recommendation cools off

Integration into Web Services -Expressing semantic relationships by -Explicit resource description (source: assertion) -Implicit resource description (source: inference) -Application logic, SPARQL patterns -Identified by URIs that are not present in the RDF store, e.g., /ancestors, /children - -Web service responses -HTTP status codes

Service Semantics: Generic Resources Thing Generic Document 303 See Other RDF HTML Content-Location: content negotiation application/rdf+xml wins text/html wins 200 OK [300 Multiple Choices]

Service Semantics: Blunt Instruments IR 1 IR 2 Resource describes IR specifies isVariationOf specifies IR 1 IR 2 Resource describes ? (Could be made explicit with RDF statements)

Thank you! Michael Panzer

RDF model: Gathering assertions about resources -Not everything has to be kept in one record in RDF -Reconstructing the whole concept graph for an RI term with SPARQL: DESCRIBE

RDF model: Gathering assertions about a resource Resulting graph (in ddc:. a skos:Concept ; skos:inScheme ; skos:prefLabel "Job ; ddc:isIndexTermOf ; skos:related.