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1 CS570 Artificial Intelligence Semantic Web & Ontology 2 2003. 12. 8 Kwak Nohyun Lee youn-ki Hwang young-bae.

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Presentation on theme: "1 CS570 Artificial Intelligence Semantic Web & Ontology 2 2003. 12. 8 Kwak Nohyun Lee youn-ki Hwang young-bae."— Presentation transcript:

1 1 CS570 Artificial Intelligence Semantic Web & Ontology Kwak Nohyun Lee youn-ki Hwang young-bae

2 2 Contents Why do we need the semantic web ? What is the semantic web? XML RDF Ontology DAML+OIL Applications Other issues

3 3 Why is the Semantic Web needed? WWW is increasing very seriously. There are some troubles in web search. It is difficult to deal with many HTML documents intelligently. We can’t extend, integrate, share information easily. So, we need something else.

4 4 What can we do in Semantic Web? Make the machine understand data in existing web Very correct search in web Inferences(New Information) Intelligent software agent Easy extension, sharing, integration of information

5 5 What is the Semantic Web? "The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation." -- Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001

6 6 Semantic Web’s Layered Structure Data:  XML Resource  RDF, RDFS Knowledge  Ontology Inference  AI  Agent

7 7 What is the Semantic Web? Web for machine(not human) Intelligent Web An extension of current web A network of knowledge(not information)  decentralized Focus on the meaning(semantics)

8 8 XML XML : Document format for computer to read easily Markup language  Contrast to HTML, user make his/her own tag in XML and XML does not focus how to show the document, but what to mean  Provide possibility of the infinite expression Tree structure

9 9 ······ XML Example Fugitive, The 1993 Auf der Flucht Fuggitivo, Il The standard Hollywood summer movie strikes back. 183,752,965 72,450,220 show title nyt review Fugitive, The The standard Hollywood ….

10 10 RDF(Resource Description Framework) Concepts An infrastructure that enables the encoding, exchange and reuse of structured metadata An application of XML  Impose structural constraints to provide unambiguous methods of expressing semantics Means for publishing both human-readable and machine-processable vocabularies

11 11 The Design Goals of RDF A simple data model Formal semantics and inference URI-based vocabulary XML-based syntax Support use of XML schema data types

12 12 The RDF Data Model Basic type  Resources : Any object that is uniquely identifiable by an URI(Uniform Resource Identifier)  Properties : a specific attribute used to describe a resource  Statement Subject Predicate Object Subject Object Property

13 13 The RDF Data Model Example1 Statement :  has a creation-date whose value is August 16, (Does machine know that the creation-date of above homepage is August 16, 1999?) RDF Statement  A subject  A predicate(property)  An object August 16, 1999

14 14 The RDF Data Model Example1 August 16, 1999

15 15 The RDF Data Model Example1 RDF/XML : August 16, 1999

16 16 The RDF Data Model Example2 Additional statements  has a creator whose value is John Smith.  has a language whose value is English.

17 17 The RDF Data Model Example2 English August 16,

18 18 The RDF Data Model Example2 August 16, 1999 English

19 19 RDF Vocabulary Description Language : RDF Schema An extension of RDF Used to declare vocabularies Provides the mechanisms needed to specify classes and properties Provides a type system for RDF Not provide a specific vocabulary of application- oriented classes

20 20 RDF Schema Summary classes  rdfs:Class  rdfs:Datatype  rdfs:Container  rdfs:Literal ... properties  rdfs:subClassOf  rdfs:subPropertyOf  rdfs:domain  rdfs:range  rdfs:comment  rdfs:member  rdfs:seeAlso ...

21 21 RDFS example1 MiniVan Van PassengerVehicle MotorVehicle Truck subClassOf

22 22 RDFS example1 The Vehicle Class Hierachy in RDF/XML

23 23 RDFS example1

24 24 RDFS example1 An instance of MotorVehicle

25 25 Knowledge Representation There exist same words having different meanings or different words having same meanings. Computer can’t understand natural languages. We need the special method for knowledge representation.

26 26 Ontology Philosophy  A theory about the nature of existence  A systematic account of existence A method for describing entities and relationships among entities An explicit specification of a conceptualization Means of describing semantics A heart of the Semantic Web The most typical kind of ontology  A taxonomy and a set of inference rules

27 27 Representation Language for Ontology Based on First Order logic  Ontololingua  Loom  Frame-Logic Based on XML(because of standardization)  SHOE(Simple HTML Ontology Extensions)  Resource Description Framework Schema Language(RDFS)  DAML(DARPA Agent Markup Language )  OIL(Ontology Inference Layer)  Ontology Web Language(OWL)

28 28 Why develop an ontology? To share common understanding of the structure of information among people or software agents To enable reuse of domain knowledge To analyze domain knowledge

29 29 DAML+OIL Web Ontology Language DAML(DARPA Agent Markup Language) + OIL(Ontology Inference Layer) DAML+OIL => OWL DAML or OIL is extension of RDF Schema

30 30 DAML+OIL Example every person is a man or a woman Elemens: intersectionOf unionOf minCardinalityQ maxCardinalityQ...

31 31 Application Example

32 32 Other Issues

33 33 Reference Berners-Lee, T., Hendler, J. and Lassila, O., “The Semantic Web,” Scientific American, 2001 Decker,S., Melnik, S., Van Harmelen, “The Semantic Web: the roles of XML and RDF”, IEEE Internet Computing, 2000 McGuiness, D., “DAML+OIL: an ontology language for the Semantic Web,” IEEE Intelligent Systems, 2002

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