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5 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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SKOS

Simple Knowledge Organization System

Vinit Kumar

SKOS


SKOS


“Simple Knowledge Organization System(s)”


Simple, extensible, machine
-
understandable
representation for “concept schemes”


Thesauri


Classification Schemes


Taxonomies


Subject Headings


Other types of ‘controlled vocabulary’…


Concept Scheme


[ a
concept scheme

is a
‘set of concepts'

optionally including relationships between
concepts.]



e.g. AAT, DDC, AGROVOC, CC …


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


Why ...?

Semantic Web technology can help:


Improve search facilities and reuse.


Concept
-
based search instead of text
-
based
search


Reuse each other’s concept definitions


Search across (institution) boundaries


Standard software

Basic SKOS Vocabulary


Skos:Concept Class

(this resource is a concept)


Lexical Labelling Properties

(associate concept
with a name)


Symbolic Labelling

(associate concept with
symbols)


Semantic Relationship Properties

(relationships
between concepts)


Documentation Properties

(definitions and
change notes)


Subject Indexing
(connecting an information
resource to terminology, dc:subject)

Traditional Thesaurus to SKOS
Mapping


Concept gets a URI, not a name


Lexical Labeling = names (not new concepts)


Skos:prefLabel


Skos:altLabel (Used For)


Relationship Labeling between concepts


Skos:broader


Skos:narrower


Skos:related


Documentation such as Scope notes


Skos:scopeNote


Skos:definition

RDF Graph Representation

SKOS Status


Development history


Initiated by Semantic Web Advanced Development for Europe
project (SWAD
-
E) in 2003


Public development process and open developer community


Driven by W3C Semantic Web Best Practices and Deployment
Working Group since 2004



SKOS Core status


1
st

Public Working Draft May, 2005


RDF Vocabulary and Guidelines for KOS Conversion also
available




Standardization goal


W3C Working Group Note


W3C Recommendation track?


RDF/XML

Using the UK Archival Thesaurus

<rdf:RDF


xmls:rdf=http://www.w3.org/1999/02/22
-
rdf
-
syntax
-
ns#


xmlns:rdfs=http://www.w3.org/2000/01/rdf
-
schema#


xmlns:skos=http://www.w3.org/2004/02/skos/core#>


<skos:Concept
rdf:about=”http://www.ukat.org.uk/thesaurus/concept/1750”>



<skos:prefLabel>
Economic cooperation
</skos:prefLabel>



<skos:altLabel>
Economic co
-
operation
</skos:altLabel>



<skos:scopeNote>Includes cooperative measures in
banking, trade,

industry, etc. between and among
countries.</skos:scopeNote>



<skos:broader
rdf:resource=http://www.ukat.org.uk/thesaurus/concept/




3000”>
[Economic policy]



<skos:narrower
rdf:resource=http://www.ukat.org.uk/thesaurus/concept/



3022”>
[industrial cooperation
]



<skos:narrower
rdf:resource=http://www.ukat.org.uk/thesaurus/



concept/3500>
[Economic integration]



<skos:inScheme rdf:
resource=http://www.ukat.org.uk/thesaurus/>


</skos:Concept>

</rdf:RDF>

Let us take some examples

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

1.
Identify

2.
Describe

3.
Publish

Identify


Step 1: Identify concepts…


http://www.example.com/concepts#love

http://www.example.com/concepts#awe

http://www.example.com/concepts#joy



Describe


Step 2: Describe…

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)

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

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

Thesaurus (RT)

Love

RT Beauty



(“RT” = Related Term)


Beauty

RT Love



(RT only between preferred terms)

Related

codified

<rdf:RDF


xmls:rdf=http://www.w3.org/1999/02/22
-
rdf
-
syntax
-
ns#


xmlns:rdfs=http://www.w3.org/2000/01/rdf
-
schema#


xmlns:skos=
http://www.w3.org/2004/02/skos/core
#


xmlns:ex=http://www.example.com/concepts#>


<skos:Concept
rdf:about=”http://www.example.com/concepts#love”>



<skos:prefLabel>
Love
</skos:prefLabel>



<skos:altLabel>
Affection
</skos:altLabel>



<skos:scopeNote>
Strong feelings of attraction
towards, and affection for, another adult, or great
affection for a friend or family
member.
</skos:scopeNote>



<skos:broader
rdf:resource=http://www.example.com/concepts#emotion
”>
[
Emotion
]



<skos:related
rdf:resource=http://www.example.com/concepts#beauty”
>
[
Beauty
]





<skos:inScheme rdf:
resource=http://www.example.com/concepts/>


</skos:Concept>

</rdf:RDF>

More Documentation Properties


skos:note

e.g. ‘I’m eating 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


Organize a set of concepts into a
concept
scheme



Add metadata about the scheme


Title


Rights


creator

Concept Scheme

Top Concepts

Subject Indexing


One of the main uses of concept scheme is to
index documents, pictures, …



skos:subject

Spotted Bowerbird

Subject

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

Story so far ...

Conceptual

Resources

skos:concept

Concept

schemes

skos:conceptScheme, skos:inscheme, skos:hasTopConcept

Lexicals

lables

skos:prefLable, skos:altLable, skos:hiddenLable

Documentation

Properties

skos:note, skos:scopeNote, skos:definition, skos:example,
skos:historyNote, skos:changeNote, skos:editorialNote


Semantic

Relations

skos:semanticRelation, skos:broader, skos:narrower,
skos:related, skos:broaderTransitive,
skos:narrowerTransitive

Lable

Relation

skos:LabelRelation, skos:seeLabelRelation,
skos:labelRelated

Concept

Collection

skos:Collection, skos:OrderedCollection, skos:member,
skos:memberList

Concept

Mapping

Relation

skos:mappingRelation, skos:broadMatch,
skos:narrowMatch,


skos:relatedMatch,
skos:exactMatch

Reference : http://www.w3.org/TR/2008/WD
-
skos
-
reference
-
20080125/

Issues in new draft

(Jan 2008)


Symbolic

Labels


Previous drafts of the SKOS specification included the properties
skos:prefSymbol
and

skos:altSymbol

as
"symbolic labeling properties"
. These
features are considered to be at risk by the Working Group.


Subject Indexing


Previous drafts of the SKOS specification included the properties
skos:subject,
skos:isSubjectOf, skos:primarySubject and skos:isPrimarySubjectOf

as
"subject indexing properties"
. These features are considered to be at risk by the
Working Group.


Published Subject Indicators


Previous drafts of the SKOS specification included the property
skos:subjectIndicator
, which was intended as a bridge between SKOS and
topic maps. This feature is considered to be at risk by the Working Group.


Notations
!!!


There is currently no explicit support in the SKOS data model or definition of
best practice for providing
"notations"
, which are codes used in some thesauri
and classification schemes.


OWL vs. SKOS Core


OWL is the language of the Semantic Web.


Why do you need SKOS if you have OWL?


SKOS Core …

… more flexible, less demanding approach to
modelling concepts

… better suited to types of KOS mentioned

...requiring little or no remodelling to express in RDF

… therefore low cost, while adding value through simple
benefits of RDF/semantic web approach.


In two lines


OWL is a W3C
recommendation


logic
-
oriented


Powerful inference


Precise semantics


SKOS Core
Complements OWL


Language
-
oriented


Less powerful inference


Flexible semantics