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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
Sohn Jong-Soo
Intelligent Information System lab.Department of Computer ScienceKorea University
Ontology Languages
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
Index
1. Ontology2. XML3. RDF4. OIL5. DAML6. OWL
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
1. Ontology
Definition : Formal, explicit specification of a a shared conceptualization
Ontology can be used and shared by agents
Ontology languages■ To be understood by humans intuitively■ Capturing of meaning (semantics) of data■ Inference mechanism with completeness,
preciseness and efficiency■ Interoperability and compatibility
Combined with web languages s.a. XML and RDF
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
1. Ontology
Crucial role in enabling web-based knowledge processing, sharing and reuse■ Human-beings and machines communicate each
other common understanding of topics between people and
applications
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
1. Ontology
Conceptual structures for machine processible data on the web■ Formal tools to structure semantic data■ Formal conceptualizations of particular domains
Metadata schema with controlled vocabulary of concepts■ Semantic metadata for web pages■ RDF & RDFS as metadata formats
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
2. XML (eXtensible Markup Language)
Standard markup language to represent the user-defined markup language
meta markup language■ Markup language to define another markup language
Simple, but flexible text-format defined from SGML
Large-scale electronic publishing to meet the role in the exchange of wide variety of data on the web and elsewhere
Hierarchical structure with tag (DTD)DTD
Document Structure(Markup Language)
XML
Document Contents (instance)
Style sheet
Style language
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
2. XML (eXtensible Markup Language)
XML related standards■ DTD (Document Type Definition)
Defines the logic structure of XML documents Defines contents & attributes of each component Defines objects
■ XSL (eXtensible Style Sheet) Defines the style to each component of XML documents Documents transformation
■ CSS (Cascading Style Sheet) Some functionality as XSL Limitation in the style definition
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
2. XML (eXtensible Markup Language)
Advantages■ Data representation ■ structured & independent■ Data sharing and interoperability■ Hierarchical, composite data
Disadvantages■ Lack of representation of relationship between
objects■ Lack of representation of data meaning■ Lack of inheritance of meaning
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
3. RDF (Resource Description Framework)
Markup language based on XML syntax Developed to representation the multiple,
various resources dispersed in the distributed web environment
Used as a basis for the other markup language Data representation : triple representation as
follow <object, property, value>
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
3. RDF (Resource Description Framework)
Advantages■ Representation of data with the meaning■ Environment in which computer can understand and
process the data■ Flexible capability to representation the meta data■ Mean of information exchange in heterogeneous
distributed environment■ Description of constants by the semantic network
Disadvantages■ Lack of affection inference mechanism■ Weak in the representation of semantic of data
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
3. RDF (Resource Description Framework)
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:s="http://iis.korea.ac.kr/schema/">
<rdf:Description about="http://iis.korea.ac.kr/Home/Sohn"><s:Creator> <rdf:Description about="http://iis.korea.ac.kr/stdId/2005020626">
<rdf:type resource="http://iis.korea.ac.kr/schema/Person"/><v:Name>Sohn JongSoo</v:Name><v:Email>[email protected]</v:Email>
</rdf:Description></s:Creator>
</rdf:Description></rdf:RDF>
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
4. OIL (Ontology Inference Layer)
Satisfies the requirement of semantic web Hierarchical layer structure for extension
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
4. OIL (Ontology Inference Layer)
Based on Frame-based System, Description Logic and Web Languages
OIL
Frame-based system:Epistemological Modeling
Primitives
Description Logics:Formal Semantics&Reasoning Support
Web language:XML and RDF-based syntax
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
4. OIL (Ontology Inference Layer)
Advantages■ Hierarchical extensions■ Effective inference mechanism based on the
Description Logic■ Well-defined semantics
Disadvantages■ Impossible to define the default-value■ Impossible to provide the meta-class■ Impossible to support the concrete domain
Limitation in the OIL extension and ontology transformation
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
5. DAML (DARPA Agent Markup Language) Based on XML and RDF
Combines the advantage of various, multiple semantic web languages■ Combination of DAML + OIL■ DAML-S
Automatic Web Service retrieval and execution
■ DAML-L Logic representation
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
5. DAML (DARPA Agent Markup Language) Advantages
■ Powerful in the representation of meaning and constraints
■ Support for the XML-Schema data type■ Support well-defined semantics■ Support default value
Disadvantages■ Can’t exclude the RDF and XML■ Can’t be formal language■ Less extensible compared with OIL
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
5. DAML (DARPA Agent Markup Language)
<?xml version=”1.0”?> <rdf:RDF xmlns:rdf=”http://www.w3.org/1999/02/22/-rdf-syntzs-ns#” xmlns:rdfs=”http://www.w3.org/TR/1999/PR-rdf-schema-19990303#” xmlns:daml=”http://www.daml.org/2001/03/daml+oil#” xmlns = “http://www.daml.org/2001/03/daml+oil#”>
<daml:Ontology rdf:about=””> <daml:versionInfo>1.0</daml:versionInfo> <daml:import rdf:resource=”http://schema.org/base# “/> </daml:Ontology>
<daml:Class rdf:ID=”boy-friend”> <rdfs:subClassof rdf:resource=”#Male” /> <rdfs:subClassOf> <daml:onProperty rdf:resource=”@has” /> <daml:hasClass redf:resource=”#girl-friend” /> </rdfs:subClassOf> </daml:Class>
<daml:Class rdf:ID=”Animal”> <rdfs:label>Animal</rdfs:label> </daml:Class>
<daml:Class rdf:ID=”girl-friend”> <rdfs:subClassOf rdf:resource=”#Female”/> </daml:Class>
<daml:Class rdf:ID=”Male”> <rdfs:subClassOf rdf:resource=”#Animal”/> <daml:disjointWith rdf:resource=”#Female”/> </daml:Class>
<daml:Class rdf:ID=”Female”> <rdfs:subClassOf rdf:resource=”#Animal”/> <daml:disjointWith rdf:resource=”#Male”/> </daml:Class>
</rdf:RDF>
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
6. OWL (Web Ontology Language)
Three species of OWL■ OWL full is union of OWL syntax and RDF■ OWL DL restricted to FOL fragment (¼ DAML+OIL)■ OWL Lite is “easier to implement” subset of OWL DL
Semantic layering■ DL semantics officially definitive
OWL DL based on SHIQ Description Logic■ In fact it is equivalent to SHOIN(Dn) DL
OWL DL Benefits from many years of DL research■ Well defined semantics■ Formal properties well understood (complexity,
decidability)■ Known reasoning algorithms■ Implemented systems (highly optimised)
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
6. OWL (Web Ontology Language)
Relationships between classes■ equivalentClass■ subClassOf■ Intersection, union, complement, disjunction
Relationships between instances■ sameAs, differentFrom
Properties of properties■ Domain, Range■ Cardinality■ Transitive, Symmetric■ allValuesFrom, someValuesFrom■ Functional, InverseFunctional
Relationships between properties■ subPropertyOf■ inverseOf
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
6. OWL (Web Ontology Language)
RDFS syntax
<owl:Class> <owl:intersectionOf rdf:parseType=" collection"> <owl:Class rdf:about="#Person"/> <owl:Restriction> <owl:onProperty rdf:resource="#hasChild"/> <owl:toClass> <owl:unionOf rdf:parseType=" collection"> <owl:Class rdf:about="#Doctor"/> <owl:Restriction> <owl:onProperty rdf:resource="#hasChild"/> <owl:hasClass rdf:resource="#Doctor"/> </owl:Restriction> </owl:unionOf> </owl:toClass> </owl:Restriction> </owl:intersectionOf></owl:Class>
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
7. Conclusion
온톨로지를 표현하는 언어■ 많은 온톨로지 언어 중 중요하게 연구된 것을 위주로 조사■ 소개된 것 외에도 Ontolingua, SHOE, TopicMap 등이 있음
W3C 의 표준화 추세■ W3C 에서 표준으로 제정한 OWL 이 가장 유력해 보임■ OWL 에 대한 연구가 가장 활발■ OWL 을 확장하여 표현력을 높이는 노력이 보임
My impression■ 비교적 예전의 언어를 이용하여 example 을 만들기가 쉽지
않았음■ 시맨틱 웹 및 지능형 웹 서비스의 과거 및 현재를
돌아봄으로써 발전 방향에 대하여 다시한번 생각할 수 있는 계기 마련
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Dept. Computer Science, Korea Univ.Dept. Computer Science, Korea Univ. Intelligent Information System Lab.Intelligent Information System Lab.
Thank you