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Dhaval Patel 2 nd Year Student School of IT IIT Kharagpur

RDF For Semantic Web. Dhaval Patel 2 nd Year Student School of IT IIT Kharagpur. Presentation Outline. Introduction Syntactic Web Semantic Web Basic RDF Terminology RDFS Reference. Introduction. TBL’s Original vision of the Web

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Dhaval Patel 2 nd Year Student School of IT IIT Kharagpur

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  1. RDF For Semantic Web Dhaval Patel 2nd Year Student School of IT IIT Kharagpur patelc@sit.iitkgp.ernet.in

  2. Presentation Outline • Introduction • Syntactic Web • Semantic Web • Basic RDF Terminology • RDFS • Reference patelc@sit.iitkgp.ernet.in

  3. Introduction TBL’s Original vision of the Web ……a goal of the Web was that, if the interaction between person and hypertext could be so intuitive that the machine-readable information space gave an accurate representation of the state of people's thoughts, interactions, and work patterns, then machine analysis could become a very powerful management tool, seeing patterns in our work and facilitating our working together through the typical problems which beset the management of large organizations….. (from w3c) Realising this vision, which has become known as the “Semantic Web” patelc@sit.iitkgp.ernet.in

  4. Syntactic Web • Current Web Contents are represented using • Natural Language (English…) • Graphics, Multimedia • Human can • Process this information easily • Combine information easily from various source (Even information is represented using different Technologies / Format) • For Machine • Difficult to make a sense from image • Drawing Analogy automatically is Difficult and many more… • Example: False Hit on Google Search Engine patelc@sit.iitkgp.ernet.in

  5. Semantic Web …An article in May 2001 issue of Science and Technology at Scientific American… Article Title The Semantic Web A new form of Web content that is meaningful to computers will unleash a revolution of new possibilities Author Tim Berners-Lee, James Hendler and Ora Lassila patelc@sit.iitkgp.ernet.in

  6. Definition • Semantic Web is • Extension of the current Web • Information is given well-defined meaning • Enabling computers and people to work in cooperation • Aim of Semantic Web • Medium of data and information that can be processed automatically • Imp. For Semantic Web • Knowledge Representation • Examples • Automatic Assistance, Data Integration, Digital Library, Semantic of Web Services • (“find me the most elegant credit card verification service?”) patelc@sit.iitkgp.ernet.in

  7. patelc@sit.iitkgp.ernet.in

  8. Giant Working for Semantic Web • Tim Berners-Lee • Dan Brickley • Dan Connolly • Sandro Hawke • Jose Kahan • Marja Koivunen, • Eric Miller • Eric Prud'hommeaux patelc@sit.iitkgp.ernet.in

  9. What is Needed? • Each resource describe itself • Means Provide information • It is also Called as Meta Data • Meta Data is in machine process able format • Vocabulary about the meta data should be defined • Agent is able to reason about the meta data • How to make Metadata Machine Process able Format The “Semantic Web” is a metadata based infrastructure for reasoning on the Web patelc@sit.iitkgp.ernet.in

  10. Semantic Web is Not • AI on Web • Use element of Logic • SW is mainly about the representing and characterizing metadata • AI is using the Metadata of SW • SW Principles • Any abstract thing can have a URI#xxx • Vocabularies can merge and be replaced with time • Anyone can say anything about anything • No one system knows everything • Design must be minimalist patelc@sit.iitkgp.ernet.in

  11. RDF – Resource Description Framework • RDF is graphical formalism • For representing metadata • It is the “Official” W3C format • For describing the semantics of information in a machine accessible way • It represent metadata as a set of statements • Statements • Statements are <subject, properties, object> triples • Subject = Object = Resource (An element, URI, Literal) • (a document, a picture, a paragraph on the Web) • Statements describe properties of Resource • Properties is directed relations between two resources • Properties themselves are also resources (URIs) patelc@sit.iitkgp.ernet.in

  12. RDF Graph patelc@sit.iitkgp.ernet.in

  13. XML Representation of RDF Graph patelc@sit.iitkgp.ernet.in

  14. Encoding Style of RDF Graph «Element for #FullSlide» «Element for graphics Type» Chart «/Element for graphics Type» «/Element for #FullSlide» «Element for #FullSlide» «Element for labelledBy» «Element for #BottomLegend» «/Element for labelledBy» «/Element for #FullSlide» patelc@sit.iitkgp.ernet.in

  15. Example <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <rdf:Description rdf:about="#FullSlide"> <axsvg:labelledBy> <rdf:Description rdf:about="#BottomLegend"/> </axsvg:labelledBy> </rdf:Description> <rdf:RDF> patelc@sit.iitkgp.ernet.in

  16. Chaining of Resource <rdf:Description rdf:about="#FullSlide"> <axsvg:labelledBy> <rdf:Description rdf:about="#BottomLegend"/> </axsvg:labelledBy> </rdf:Description> <rdf:Description rdf:about="#BottomLegend"> <axsvg:isAnchor>True</axsvg:isAnchor> </rdf:Description> patelc@sit.iitkgp.ernet.in

  17. Simplification <property> <rdf:Description rdf:about="URI"/> </property> Simplified As <property rdf:resource="URI"/> patelc@sit.iitkgp.ernet.in

  18. Programming Practice • Python + RDFLib • PHP • Java patelc@sit.iitkgp.ernet.in

  19. RDF Schema (RDFS) • Also known as RDF Vocabulary Description Language (RDFS) • In RDF, • Some words may be incorrect or unknown • Interpretation is an arbitrary binary relation • Not given any special meaning to vocabulary such as sub-Class-Of or type • RDF Schema defines “schema vocabulary” that supports definition of ontologies • Gives “extra meaning” to particular RDF properties and resources (such as subClassOf) • This “extra meaning”, or semantics, specifies how a term should be interpreted patelc@sit.iitkgp.ernet.in

  20. RDF Schema Terms (Construct) • Class • Property • type • Sub Class Of • range • domain • <Person, type, Class> • <hasColleague, type, Property> • <Professor, subClassOf, Person> • <Carole, type, Professor> • <hasColleague, range, Person> • <hasColleague, domain, Person> patelc@sit.iitkgp.ernet.in

  21. Vocabulary patelc@sit.iitkgp.ernet.in

  22. Point to be Taken care • No Distinction Between Class and Resource • <Species, type, Class> • <Lion, type, Species> • <Leo, type, Lion> • Properties has themselves properties • No Difference Between Construct and user defined Construct • <Property , type, Class> patelc@sit.iitkgp.ernet.in

  23. Continue …… Problem with RDFS No transitive, inverse or symmetrical ( IsPartof, hasPart) Ontology Web Ontology Language patelc@sit.iitkgp.ernet.in

  24. Reference [1] http://www.sciam.com/article.cfm [2] http://www.w3.org/RDF [3] http://www.w3.org/Consortium/Offices/Presentations/RDFTutorial [4] http://www.w3.org/2001/sw/EO [5] http://www.w3.org/2002/Talks/04-sweb-sloan/ patelc@sit.iitkgp.ernet.in

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