SKOS Catch 25nov05

SKOS TutorialCatch: 

SKOS Tutorial Catch Mark van Assem, Antoine Isaac Vrije Universiteit Amsterdam Based on slides by Alistair Miles CCLRC Rutherford Appleton Laboratory http://isegserv.itd.rl.ac.uk/cvs-public/skos/press/dc2005/tutorial.ppt Semantic Web Best Practices and Deployment

Intro: 

Intro SKOS “Simple Knowledge Organisation System(s)” Simple, extensible, machine-understandable representation for “concept schemes” Thesauri Classification Schemes Taxonomies Subject Headings Other types of ‘controlled vocabulary’…

SKOS Development: 

SKOS Development Developed by W3C’s Semantic Web Best Practices-WG Draft for Working Group Note Design: public, consensus-driven, open community, email Input from actual vocabulary maintainers

Motivation: 

Motivation Semantic Web technology can help improve search facilities and reuse: Concept-based search instead of text-based search 2. Reuse each other’s concept definitions 3. Search across (institution) boundaries 4. Standard software

1. Concept Search: 

1. Concept Search Painter Domenikos Theotocopoulos = “El Greco” (nickname) Some indexers use “El Greco”, others “D. Theotocopoulos” Searching for “El Greco” does not give all results Solution: one concept with different lexical labels.

Example: 

Example N.B.: vocabulary with identifiers for preferred terms and indexing with identifiers accomplishes this

2. Reuse: 

2. Reuse Reuse existing concept “El Greco” Req. 1: one “exchange syntax” Req. 2: “point” at other concepts

3. Search Across Boundaries: 

3. Search Across Boundaries Search for concept “El Greco” returns paintings from both institutions  Same requirements

4. Standard Software: 

4. Standard Software If all concept schemes use same “exchange syntax” and “structure”, standardized software can be built to: Display/browse concept scheme Annotate with concept scheme Integrate data from 2 institutions using standard concept schemes (“search across boundaries”)  Req. 3: Similar structures (graphs) in exchange syntax

Why SKOS helps: 

Why SKOS helps SKOS uses RDF sharing “graphs” in distributed environment (intranet/internet) Uses URIs for “pointing” (identifying) Easy to extend by anyone for specific purposes “exchange syntax” “Point at concept” SKOS: set of classes and properties to describe concept schemes Produce “similar graphs”  “Same structures”/ clear what graph means Disadvantage: unusual concept schemes don’t fit into SKOS (original structure too complex)

Quick RDF: a ‘Statement’: 

Quick RDF: a ‘Statement’ A.K.A. a ‘Triple’

Quick RDF: a ‘Graph’: 

Quick RDF: a ‘Graph’

Quick RDF: exchange syntax: 

Quick RDF: exchange syntax RDF Graphs can be exchanged in XML (and other formats) Alternative ways to represent & exchange the same graph Here we only discuss RDF graphs, exchange syntax is “lower-level” technical issue

Controlled Vocabulary: 

Controlled Vocabulary Love Strong feelings of attraction towards, and affection for, another adult, or great affection for a friend or family member. Awe A feeling of great respect sometimes mixed with fear or surprise. Joy A feeling of bliss and great happiness.

Converting into SKOS graph: 

Converting into SKOS graph Identify Describe Publish

Identify: 

Identify Step 1: Identify concepts… http://www.example.com/concepts#love http://www.example.com/concepts#awe http://www.example.com/concepts#joy

Describe: 

Describe Step 2: Describe…

Publish: 

Publish Step 3: Publish… Put the file on a web server for programs to download & process Put the file on special RDF server on which you can query with SQL-like language: Select * from … Where …

Thesaurus (USE/UF): 

Thesaurus (USE/UF) Love (preferred term) UF Affection Affection (non-preferred term) USE Love (“USE” directs user from non-pref term to pref-term that should be used in indexing and search)

Lexical Labels: 

Lexical Labels

Thesaurus (BT/NT): 

Thesaurus (BT/NT) Love BT Emotion (“BT” = Broader Term) Emotion NT Love (“NT” = Narrower Term) NT Awe NT Joy (BT/NT only between preferred terms)

Broader/Narrower: 

Broader/Narrower

Thesaurus (RT): 

Thesaurus (RT) Love RT Beauty (“RT” = Related Term) Beauty RT Love (RT only between preferred terms)

Related: 

Related

Story So Far…: 

Story So Far… Basic Structure skos:Concept Lexical Labelling skos:prefLabel, skos:altLabel Documentation skos:definition Semantic Relations skos:broader, skos:narrower, skos:related

More Documentation Properties: 

More Documentation Properties skos:note e.g. ‘I’m going bananas’ skos:definition e.g. ‘A long curved fruit with a yellow skin and soft, sweet white flesh inside.’ skos:example e.g. ‘A bunch of bananas.’ skos:scopeNote e.g. ‘Only use for the western family of bananas’ skos:historyNote e.g. ‘Introduced 1986.’

Concept Schemes: 

Concept Schemes Organise a set of concepts into a concept scheme Add metadata about the scheme Title Rights creator

Concept Scheme: 

Concept Scheme

Top Concepts: 

Top Concepts

Subject Indexing: 

Subject Indexing One of the main uses of concept scheme is to index documents, pictures, … skos:subject

Spotted Bowerbird: 

Spotted Bowerbird

Subject: 

Subject

Node Labels in Hierarchy: 

Node Labels in Hierarchy milk <milk by source animal> (node label) buffalo milk cow milk goat milk sheep milk (Organize terms into “subcategories” to help users find relevant term; “guide terms”; node label itself not meant for indexing)

Representation in SKOS: 

Representation in SKOS

Story So Far…: 

Story So Far… Documentation Properties skos:note, skos:definition, skos:example, skos:scopeNote, skos:historyNote Concept Schemes skos:ConceptScheme, skos:hasTopConcept, Subject Indexing skos:subject Node Labels skos:Collection, skos:member More properties not shown here

Extensions : 

Extensions SKOS Core can be extended by refining the classes and properties of the SKOS RDF Schema E.g. North-Holland BT Netherlands is a part-of relationship

Example: 

Example

Exercise: 

Exercise Groups of six, separated into group A and group B Given a “concept scheme” (text), create SKOS graph for it Groups A: give SKOS graph (not the text) to group B (and vice versa) Re-create “concept scheme” (text) from SKOS graph

SKOS Graph Legend: 

SKOS Graph Legend Concept in concept scheme String Arrow types: broader, narrower, related, broaderPartOf, … prefLabel, altLabel, scopeNote, definition, historyNote, … Introduce new “arrow types” if required “text”

Possible Exercise Solution (Brinkman): 

Possible Exercise Solution (Brinkman)

Possible Exercise Solution (NBC): 

Possible Exercise Solution (NBC)

Conclusions from exercise: 

Conclusions from exercise Different syntax/structures cause problems SKOS graph makes graphs for concept schemes more uniform Not trivial how to convert original source into SKOS graph But once agreement on that  interoperability

Last Point: 

Last Point Do we expect everyone to change to SKOS? No, internal formats and SKOS can co-exist Export to SKOS RDF for interoperability Right tool for the right job!

Links: 

Links SKOS Core Homepage http://www.w3.org/2004/02/skos/core SKOS Core Guide http://www.w3.org/TR/swbp-skos-core-guide SKOS Core Vocabulary Specification http://www.w3.org/TR/swbp-skos-core-spec Mailing list mailto:public-esw-thes@w3.org http://lists.w3.org/Archives/Public/public-esw-thes/