Alistair Miles 
Rutherford Appleton Laboratory UK (CCLRC)
SWAD-Europe
SWBPD-WG
(irc: aliman)

SKOS

Expressing concept schemes (thesauri, classification schemes, controlled vocabularies, structured vocabularies, terminologies, glossaries, taxonomies ...) in RDF


History

The Beginnings of SKOS ...

SWAD-Europe: Thesaurus WP

Designing an RDF vocabulary for expressing content and structure of thesauri

Took TIF (Thesaurus Interchange Format, from LIMBER project) as starting point

Changed name: SKOS (Simple Knowledge Organisation Systems)
	- common meta-model for conceptual KOS types (not just thesauri)
	- SW is about publishing data (not 'data interchange')
	- RDF is not a file format

SWAD-E Published 2 RDF vocabularies (& supporting docs) ...

SKOS Core
	Basic content and structure of thesauri etc.
	
SKOS Mapping
	Inter-thesaurus mapping

After SWAD-E ...

SWBPD-WG: 'Porting Thesauri (to SW)' Task Force [PORT]

Objective:
	Publishing an RDF vocabulary for thesauri etc.

Continue development of SKOS Core, publish as W3C WG Note

Two documents (at editor's draft):
	SKOS Core Guide
	SKOS Core Vocabulary Specification

Also (at editor's draft):
	Quick Guide to Publishing a Thesaurus on the Semantic Web

... and we're almost there !!



SKOS Core Overview

@prefix skos: <http://www.w3.org/2004/02/skos/core#>.

Classes ... 
	skos:Concept
	skos:ConceptScheme
	...

Properties ...

[Labelling]
	skos:prefLabel, skos:altLabel, skos:hiddenLabel, skos:prefSymbol, skos:altSymbol

[Documentation]
	skos:definition, skos:example, skos:scopeNote, skos:changeNote, skos:historyNote ...

[Relationships between conceptual resources]
	skos:broader, skos:narrower, skos:related

[Subject indexing]
	skos:subject, skos:isSubjectOf, skos:primarySubject, skos:isPrimarySubjectOf ...

... and some other stuff :)


Interesting Stuff for SWIG

Semantic Web Vocabulary Management

... how to manage an evolving vocabulary ...?
... dropped a discrete versioning model for the FOAF versioning model
	- terms have stability: unstable, testing, stable
	- different bits of the vocab can have different stability
... still do not record term version history (a la DC)

... would like to see FOAF and/or DC (and/or other?) vocabulary management models formalised, with supporting RDF vocab for change management.

SWBPD-WG: Vocab Management TF ... ?


Semantic Web Vocabulary Documentation

Publish 'vocabulary specification' generated mostly by script from RDF, template based on DC & FOAF docs


Collaborative Vocabulary Development

Wanted to make SKOS Core a community effort, involve the community stakeholders and potential users in development at the earliest possible stage.

Did outreach to build a community.

Used public-esw-thes@w3.org as development and discussion forum.

Allow both informal and semi-formal interaction via public-esw-thes@w3.org ...
	[Requirement] [Proposal] [Action]
	... take action based on consensus
	... all actions (changes) published via RSS

... but at the end of the day, changes implemented by the editors (me, danbri) by manually editing an RDF/XML file.

=> Wouldn't it be nice if we had a web tool that supported collaborative vocab development by a team of editors, and handled stuff like term stability, change and versioning ... :)


SKOS and RDFS/OWL

How to relate modelling traditions ... ?

E.g.

@prefix ex: <http://www.example.org/concepts#>.
@prefix ex2: <http://www.example.org/ontology#>.
@prefix skos: <http://www.w3.org/2004/02/skos/core#>.
@prefix foaf: <blah>.

ex:henry8 
	a skos:Concept;
	skos:prefLabel 'King Henry VIII of England';
	dc:creator 
	[
		a foaf:Person;
		foaf:name	'Alistair Miles';
	].

ex2:henry8
	a foaf:Person;
	foaf:name	'Henry Tudor';
	foaf:mbox	<mailto:henry8@tudorengland.org>.
	
ex:henry8 <???> ex2:henry8.


Collectables (& rules) ...

[unstable]

from thesauri ...

milk
	<milk by source animal>
		buffalo milk
		cow milk
		goat milk

Tricky to model (to get the semantics right and still get desired behaviour) ...
	... used custom grouping vocabulary in SKOS Core plus rules

Collectable properties ...

	(?x ?p ?c) 
	(?c skos:member ?y)
	(?p rdf:type skos:CollectableProperty)
	=>
	(?x ?p ?y)

... what is feeling about/status of RDF containers?
... rule syntax?


(PSIs) Published Subject Indicators ...

[unstable]

skos:subjectIndicator
	- point to an information resource that completely explains the identity of a non-info resource
	- and inverse functional property - can indirectly identify e.g. conceptual resources via the URI of a subject indicator document

... interop with OASIS published subjects paradigm

?


... and HTTP Range-14 ...

enough said, but still needs to get sorted.