온톨로지 개념 및 표현언어

시맨틱 웹 VoCamp 서울: 여름

온톨로지 개념 및
온톨로지 표현언어

김동범 (eastkim@gmail.com)
아이네크 시맨틱사업팀
http://www.dbdb.kr, @eastkim on twitter
2009.05.29
1

The Role of RDF on Semantic Web

Semantic
Aspect

시맨틱 웹 표준의
첫 번째 Layer
Web
Aspect

시맨틱 웹 VoCamp 서울: 여름 -2-

Why RDF model is different from the
XML model ?
 “The author of the page is Ora”
 triple(author, page, Ora)

has author
page Ora

Tim Berners-Lee (1998), http://www.w3.org/DesignIssues/RDF-XML

How would this information be typically represented
in XML?
or may be
<author> <document>
<uri>page</uri> <details>
<uri>href=“page”</uri>
<name>Ora</name>
<author>
</author> <name>Ora</name>
</author>
</details>
or may be </document>

<document href=“page”>
<author>Ora</author> <document>
</document> <author>
<uri>href=“page”</uri>
<details>
<name>Ora</name>
</details>
</author>
</document>
or may be
<document href=“http://www.w3.org/test/page” author=“Ora” />


What is the author of page?

<v>
<x>
<y>a=“pppp”</y>
<z>
<w>qqqqq</w>
</z>
</x>
</v>

has author
page Ora

b
a c


In RDF Graph

<Description about=quot;http://www.w3.org/test/pagequot; Author =quot;Oraquot; />

<?xml version=quot;1.0quot;?>
<Description about=quot;http://www.w3.org/test/page“>
<s:Author =quot;http://www.w3.org/staff/Oraquot; />
</Description>

has author
page Ora


The RDF Graph displays the same thing

<Description about=“xquot; y=“z” />

<?xml version=quot;1.0quot;?>
<Description about=“x“>
<y =“z” />
</Description>

y
x z


분산된 데이터의 웹에서….

글을 영화 ‘xxx’에
작성하다 출연하다

통합문서

Ora는 ‘page’의
저자이고, 영화 ‘xxx’에
출연했다

xxx

has author
page Ora plays in


What is ontology?

quot;formal, explicit specification of a
shared conceptualization“

“공유된 개념에 대한 형식적이고,
명시적인 명세……??”

Tom Gruber (1993)


What is ontology?

존재론 in Philosophy

즉, 온톨로지는 “존재하는 것들에 대한 설명”

그럼 존재하는 것이란 무엇일까요?

시맨틱 웹 VoCamp 서울: 여름 - 10 -

존재하는 것

Thing


스무고개…
Asia

partOf
Person
lives in
type Korea
Asia

age
Thing
works at
3X INEK
name
type
??
Corporation

정답!! >> 김동범

이와 같이 온톨로지는….

 Thing 에 제약(속성, 관계)을 가함으로써 개념을 정의

 제약이 많다 = 표현력(Expressivity)이 풍부하다

 객관적인 형식과 그 형식이 동작하는 방식을 규정 (formal)


표현력에 따른 온톨로지

 Lightweight ontologies  Heavyweight ontologies
 Concepts  type constraints on relations
 Relationships between  Cardinality constraints
Concepts
 Axioms
 IS-A Hierarchy

RDF, RDFS, OWL Lite OWL DL


온톨로지 표현 언어
RDF, RDFS, OWL


History of Ontology Language
 RDF(S)
 Developed by W3C (1999, 02)
 Ontology Inference Layer : OIL
 Developed by group of European researchers (2000, 01)

 DAML Ontology Language : DAML-ONT
 Developed by US researchers working in DAML program (2000, 10)

 Effort merged in DAML+OIL
 Developed by EU/US joint committee (2000, 12)

 W3C Web Ontology group : OWL
 W3C standard based on DAML+OIL (2002, 02)


RDF stands for
Resource : URI를 갖는 모든 것 (웹 페이지, 이미지, 동영상 등)

Description : 자원(Resource)들의 속성, 특성, 관계

Framework : 위의 것들을 기술하기 위한 모델, 언어, 문법


RDF 데이타 모델

Predicate
Subject Object : Triple Model

example
title
온톨로지 개념 및 표현언어
http://www.dbdb.kr/rdf_tutorial

author DongBeom Kim

<?xml version=“1.0”>

<RDF>
<Description about=“http://www.dbdb.kr/rdf_tutorial”>
<author>DongBeom Kim</author>
<homepage>온톨로지 개념 및 표현언어</homepage>
</Description>
</RDF>


Movie List
URI : http://movie.naver.com/


RDF Example
title director country runtime genre reviewer

007 퀀텀 오브 솔러스 마크 포스터 미국 106분 액션 genie

아내가 결혼했다 정윤수 한국 119분 멜로 eastkim

… … … … … …


<RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#”
xmlns:movie=“http://movie.naver.com/”>

<Description rdf:about=“http://movie.naver.com/007quantumofsolace”>
<movie:title>007 퀀텀 오브 솔러스</movie:title>
<movie:director>마크 포스터</movie:director>
<movie:country>미국</movie:country>
<movie:runtime>106분</movie:runtime>
<movie:reviewer>genie</movie:reviewer>
</Description>

<Description rdf:about=“http://movie.naver.com/2husbands”>
<movie:title>아내가 결혼했다</movie:title>
…
</Description>
</RDF>


RDF Main Elements
<rdf:RDF> Element
RDF 문서의 root Element

<rdf:Description> Element
about 속성을 가진 resource를 식별(기술)하기 위해 사용
Resource를 기술하기 위한 여러 Element(title, director, etc)를 포함

<RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#”
xmlns:movie=“http://movie.naver.com/”>

.
<movie:title>007 goes 오브 솔러스</movie:title>
. Description 퀀텀 here
.
</Description>

<Description rdf:about=“http://movie.naver.com/2husbands”>
<movie:title>아내가 결혼했다</movie:title>
…
</Description>
</RDF>


RDF Main Elements

 Properties as Attributes
<Description rdf:about=“http://movie.naver.com/007quantumofsolace”
movie:title=“007 퀀텀 오브 솔러스” movie:director=“마크 포스터”
movie:country=“미국” movie:runtime=“106분” movie:reviewer=“genie”
/>

 Properties as Resources

<movie:title>007 퀀텀 오브 솔러스</movie:title>
</Description>


RDF Main Elements

 rdf:
Alt, Bag, Description, ID, List, Property, Statement, Seq, XMLLiteral

about, first, nodeID, object, parseType, predicate, resource, rest, subject, type,
value, nil

 rdfs
:
Class, Container, ContainerMembershipProperty, Datatype, Literal, Resource

comment, domain, isDefinedBy, label, member, range, sellAlso, subClassOf, subPropertyOf


OWL (Web Ontology Language)

 More Expressive than RDF(S)
 Adds more vocabularies for describing properties
and classes
 Based on Description Logic

 W3C Recommendation (2004.02)


OWL 의 하위 언어들
 OWL Lite
 Subset of DL
 light-weight 한 ontology 구축에 적합

 OWL DL
 Support Description Logic segment
 Has properties for reasoning systems
 heavy-weight한 ontology 구축에 적합

 OWL Full
 Union of OWL and RDFS
 Allow free mixing of OWL with RDF Schema
 Not enforce a strict separation of classes, properties, individuals

 OWL Lite ⊂ DL ⊂ Full

OWL Lite Contructions (1)

 RDF Schema Features:  (In)Equality

 Class  equivalentClass
 rdf:Property  equivalentProperty
 rdfs:subClassOf  sameIndividualAs
 rdfs:subPropertyOf
 differentFrom
 rdfs:domain
 allDifferent
 rdfs:range
 Individual


OWL Lite Contructions (2)
 Property Type  Restricted Cardinality
Restrictions: – minCardinality (only 0 or 1)
 allValuesFrom – maxCardinality(only 0 or 1)
 someValuesFrom – cardinality (only 0 or 1)

 Class Intersection  Property Characteristics:
 intersectionOf  inverseOf
 transitiveProperty
 Datatypes  symmetricProperty
 functionalPropety
 InverseFunctionalProperty


Property type restrictions
 owl:allValuesFrom
<owl:Restriction>
<owl:onProperty rdf:resource=quot;#hasParentquot; />
<owl:allValuesFrom rdf:resource=quot;#Humanquot; />
</owl:Restriction>

hasParent
X Y
Y는 모두 Human

 owl:someValuesFrom : 부모중 적어도 한명은 Physician 이다.
<owl:Restriction>
<owl:onProperty rdf:resource=quot;#hasParentquot; />
<owl:someValuesFrom rdf:resource=quot;#Physicianquot;/>
</owl:Restriction>


Property type restrictions
 owl:inverseOf
if hasChild inverseOf hasParent and Deborah hasParent Louise
then Louise hasChild Deborah

 owl:transitiveProperty
if pair(X,Y), pair(Y,Z) are instances of transitive property P,
then pair(X,Z) is also instance of P

 owl:symmetricProperty
if pair(X,Y) is an instance of P, then pair(Y,X) is also instance of P


OWL DL, FULL Contructions
(2) Axioms:
 Class Boolean Combinations 
 oneOf of Class Expressions:
 disjointWith – unionOf
 equivalentClass – intersectionOf
(applied to class expressions) – complementOf
 rdfs:subClassOf
(applied to class expressions)

 Filler Information:
 Arbitrary Cardinality:
– hasValue
 minCardinality
 maxCardinality
 cardinality


OWL DL 표현 예제
 owl:intersectionOf
 links a class to a list of class description
 represent the “AND”

<owl:Class rdf:ID=quot;Adultquot;>
<owl:intersectionOf rdf:parseType=quot;Collectionquot;>
<owl:Class rdf:about=quot;#Personquot;/>
<owl:restriction>
<owl:onProperty rdf:resource=quot;#agequot;/>
<owl:someValuesFrom
df:resource=quot;http://www.w3.org/TR/@@/owl-ex-dt#over19quot;/>
</owl:Restriction>
</owl:intersectionOf>
</owl:Class>

Adult = Person ∩ $ age.over19


 owl:inverseOf
<owl:ObjectProperty rdf:ID=“hasChild”>
<owl:inverseOf rdf:resource=“#hasParent”/>
</owl:ObjectProperty>

 owl:FunctionalProperty
<owl:FunctionalProperty rdf:ID=quot;husbandquot;>
<rdfs:domain rdf:resource=quot;#Womanquot; />
<rdfs:range rdf:resource=quot;#Manquot; />
</owl:FunctionalProperty>

<owl:ObjectProperty rdf:ID=quot;husbandquot;>
<rdf:type rdf:resource=quot;&owl;FunctionalPropertyquot; />
<rdfs:domain rdf:resource=quot;#Womanquot; />
<rdfs:range rdf:resource=quot;#Manquot; />
</owl:ObjectProperty>


 owl:TransitiveProperty
<owl:TransitiveProperty rdf:ID=quot;subRegionOfquot;>
<rdfs:domain rdf:resource=quot;#Regionquot;/>
<rdfs:range rdf:resource=quot;#Regionquot;/>
</owl:TransitiveProperty>

 owl:SymmetricProperty

<owl:SymmetricProperty rdf:ID=quot;friendOfquot;>
<rdfs:domain rdf:resource=quot;#Humanquot;/>
<rdfs:range rdf:resource=quot;#Humanquot;/>
</owl:SymmetricProperty>


시맨틱 웹 VoCamp 서울: 여름

감사합니다 !

34

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