1 / 33

CS570 Artificial Intelligence Semantic Web & Ontology 2

CS570 Artificial Intelligence Semantic Web & Ontology 2. 2003. 12. 8 Kwak Nohyun Lee youn-ki Hwang young-bae. Contents. Why do we need the semantic web ? What is the semantic web? XML RDF Ontology DAML+OIL Applications Other issues. Why is the Semantic Web needed?.

judith-england
Télécharger la présentation

CS570 Artificial Intelligence Semantic Web & Ontology 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

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

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

  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. 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. XML Example show <show type="Movie"> <title>Fugitive, The</title> <year>1993</year> <aka>Auf der Flucht</aka> <aka>Fuggitivo, Il</aka> <review> <nyt> The standard Hollywood summer movie strikes back. </nyt> </review> <box_office>183,752,965</box_office> <video_sales>72,450,220</video_sales> </show> title review ······ Fugitive, The nyt The standard Hollywood ….

  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. 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. Property Subject Object 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

  13. The RDF Data Model Example1 • Statement : • http://www.example.org/index.html has a creation-date whose value is August 16, 1999 . • (Does machine know that the creation-date of above homepage is August 16, 1999?) • RDF Statement • A subject • http://www.example.org/index.html • A predicate(property) • http://www.example.org/terms/creation-date • An object • August 16, 1999

  14. The RDF Data Model Example1 http://www.example.org/index.html http://purl.org/dc/elements/1.1/creation-date August 16, 1999

  15. The RDF Data Model Example1 RDF/XML : <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:exterms="http://www.example.org/terms/"> <rdf:Description rdf:about="http://www.example.org/index.html"> <exterms:creation-date>August 16, 1999</exterms:creation-date> </rdf:Description> </rdf:RDF>

  16. The RDF Data ModelExample2 • Additional statements • http://www.example.org/index.html has a creator whose value is John Smith. • http://www.example.org/index.html has a language whose value is English.

  17. The RDF Data ModelExample2 http://www.example.org/index.html http://purl.org/dc/elements/1.1/creator http://www.example.org/terms/creation-date http://www.example.org/staffid/85740 August 16, 1999 http://www.example.org/terms/language English

  18. The RDF Data ModelExample2 <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:exterms="http://www.example.org/terms/"> <rdf:Description rdf:about="http://www.example.org/index.html"> <exterms:creation-date>August 16, 1999</exterms:creation-date> <exterms:language>English</exterms:language> <dc:creator rdf:resource="http://www.example.org/staffid/85740"/> </rdf:Description> </rdf:RDF>

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

  21. RDFS example1 MiniVan Truck subClassOf subClassOf subClassOf PassengerVehicle Van subClassOf subClassOf MotorVehicle

  22. RDFS example1 The Vehicle Class Hierachy in RDF/XML <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"> <rdf:Description rdf:ID="MotorVehicle"> <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/> </rdf:Description> <rdf:Description rdf:ID="PassengerVehicle"> <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/> <rdfs:subClassOf rdf:resource="#MotorVehicle"/> </rdf:Description>

  23. RDFS example1 <rdf:Description rdf:ID="Truck"> <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/> <rdfs:subClassOf rdf:resource="#MotorVehicle"/> </rdf:Description> <rdf:Description rdf:ID="Van"> <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/> <rdfs:subClassOf rdf:resource="#MotorVehicle"/> </rdf:Description> <rdf:Description rdf:ID="MiniVan"> <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/> <rdfs:subClassOf rdf:resource="#Van"/> <rdfs:subClassOf rdf:resource="#PassengerVehicle"/> </rdf:Description> </rdf:RDF>

  24. RDFS example1 An instance of MotorVehicle <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#“xmlns:ex="http://example.org/schemas/vehicles"> <rdf:Description rdf:ID="companyCar"> <rdf:type rdf:resource="http://example.org/schemas/vehicles#MotorVehicle"/> </rdf:Description> </rdf:RDF>

  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. 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. 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. 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. 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. DAML+OIL Example <daml:Class rdf:about="#Person"> <rdfs:comment>every person is a man or a woman</rdfs:comment> <daml:disjointUnionOf rdf:parseType="daml:collection"> <daml:Class rdf:about="#Man"/> <daml:Class rdf:about="#Woman"/> </daml:disjointUnionOf> </daml:Class> Elemens: intersectionOf unionOf minCardinalityQ maxCardinalityQ ...

  31. Application Example

  32. Other Issues

  33. Reference • http://www.w3.org/ • http://www.w3.org/2001/sw/ • http://www.w3.org/RDF/ • http://www.w3.org/XML/ • http://www.daml.org/ • 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

More Related