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Intro to the Semantic Web (Peter Snyder - CSG339 - NorthEastern University)

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Slides from the presentation I gave in my Information Retrieval class at NorthEastern in June 2009. The class was taught by Javed Aslam.

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Intro to the Semantic Web (Peter Snyder - CSG339 - NorthEastern University)

  1. 1. Intro to the Semantic Web Peter Snyder snyderp@gmail.com 1
  2. 2. Outline • What Is the Semantic Web? • What Problem is it Trying to Solve? • How does it Solve the problem? 2
  3. 3. What is the SW? • Effort to 1. make data on the web machine friendly 2. using existing open technologies 3. in order to aid information retrieval 3
  4. 4. What is the SW? .... • Made up of - XML - XML Schema - RDF - RDF Schema / OWL - SPARQL 4
  5. 5. Outline • What Is the Semantic Web? • What Problem is it Trying to Solve? • How does it Solve the problem? 5
  6. 6. What is the Problem? • Web is human oriented • All nonsense to machines • Humans waste time 6
  7. 7. Example http://www.peteresnyder.com/fake <div> <h1>My Homepage</h1> <p>Hi, I'm Peter E. Snyder. <p>I live in Cambridge. <p>I like the band The Fall! <p>I love professional wrestling! </div> 7
  8. 8. Outline • What is the semantic web? • What problem is it trying to solve? • How does it solve the problem? 8
  9. 9. Solution • Basic Track (Microformats) • W3C Recommendation (Alphabet Soup) 9
  10. 10. Microformats <div class="vcard"> <p> <a class="url" href="http://www.peteresnyder.com"> http://www.peteresnyder.com </a> </p> <p> <strong>Name:</strong> <span class="fn">Peter Snyder</span> </p> <p> <strong>City:</strong> <span class="locality">Cambridge</span> </p> </div> 10
  11. 11. W3C Recommends... • XML • XML Schema • RDF • RDF Schema / OWL • SPARQL 11
  12. 12. XML <?xml version="1.0"?> <person> <name>Peter Snyder</name> <website>http://www.peteresnyder.com<website> <city>Cambridge</city> <interests> <interest>The Fall</interest> <interest>Professional Wrestling</interest> </interests> </person> 12
  13. 13. XML Schema XML Schema <?xml version="1.0"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="person"> <xs:complexType> <xs:sequence> <xs:element name="website" type="xs:string"/> <?xml version="1.0"?> <xs:element name="name"xmlns:pes=”http://www.peteresnyder.com/fake_schema”> <person type="xs:string"/> <xs:element name="city" type="xs:string"/> <pes:name>Peter Snyder</pes:name> ... <pes:website>http://www.peteresnyder.com<pes:website> <pes:city>Cambridge</pes:city> <pes:interests> <pes:interest>The Fall</pes:interest> <pes:interest>Professional Wrestling</pes:interest> </pes:interests> </pes:person> 13 XML Document
  14. 14. RDF • Resource Description Framework • Description of relationships (taxonomy) • Triplets - subject: thing being described (URI) - predicate: what the relationship is - object: the object being related to 14
  15. 15. RDF Cont. <urn:name:peteresnyder> <name> "Peter Snyder" . <urn:name:peteresnyder> <city> "Cambridge" . <urn:name:peteresnyder> <likes> "The Fall" . <?xml version="1.0"?> <rdf:RDF> <Human rdf:about="urn:name:peteresnyder"> <name>Peter E Snyder</name> <city>Cambridge</city> <likes>The Fall</likes> ... 15
  16. 16. RDF Schema / OWL • Defines a standard way that things interact (ontology) • Common Examples - Dublin Core: Publishing - Friend of a Friend (FOAF): People - OWL is RDFS+ 16
  17. 17. RDFS / OWL Cont. FOAF RDF Schema <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:foaf="http://xmlns.com/foaf/0.1/"> <foaf:Person rdf:about="urn:name:peteresnyder"> <foaf:homepage rdf:resource="http://www.peteresnyder.com"/> <foaf:givenname>Peter</foaf:givenname> <foaf:family_name>Snyder</foaf:family_name> <foaf:interest>The Fall</foaf:interest> .... 17
  18. 18. SPARQL • SPARQL Protocol and RDF Query Language • SQL like language for getting data out of RDF connections / graphs 18
  19. 19. SPARQL Cont. <foaf:Person rdf:about="urn:name:markesmith"> <foaf:Person rdf:about="urn:name:tinafey"> <foaf:homepage rdf:resource="http://www.peteresnyder.com"/> <foaf:Person rdf:about="urn:name:peteresnyder"> <foaf:homepage rdf:resource="http://www.peteresnyder.com"/> <foaf:givenname>Peter</foaf:givenname> <foaf:homepage rdf:resource="http://www.peteresnyder.com"/> <foaf:givenname>Peter</foaf:givenname> <foaf:family_name>Snyder</foaf:family_name> <foaf:givenname>Peter</foaf:givenname> <foaf:family_name>Snyder</foaf:family_name> <foaf:interest>The Fall</foaf:interest> <foaf:family_name>Snyder</foaf:family_name> <foaf:interest>The Fall</foaf:interest> ... <foaf:interest>The Fall</foaf:interest> ... ... + PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?givenname ?family_name WHERE { ?x foaf:interest "The Fall"} = ?givenname ?family_name “Peter” “Snyder” “Mark” “Smith” 19
  20. 20. Conclusion Current Web Semantic Web <div> <?xml version="1.0"?> <h1>My Homepage</h1> <rdf:RDF xmlns:foaf="http://xmlns.com/foaf/0.1/"> <p>Hi, I'm Peter E. Snyder. <foaf:Person rdf:about="urn:name:peteresnyder"> <foaf:homepage rdf:resource="http:// <p>I live in Cambridge. www.peteresnyder.com"/> <p>I like the band The Fall! <foaf:givenname>Peter</foaf:givenname> <p>I love professional <foaf:family_name>Snyder</foaf:family_name> wrestling! <foaf:interest>The Fall</foaf:interest> </div> ... 20

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