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Semantic Web

Semantic Web. Quratulain Rajput Faculty of Computer Science, IBA Spring2013. RDF. To represent web as: “ the web of real world object rather than only web of documents.”. RDF. Construction of URI Scheme:[//authority]path[?query][#fragment] [Note: path and fragment are optional.]

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Semantic Web

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  1. Semantic Web Quratulain Rajput Faculty of Computer Science, IBA Spring2013

  2. RDF • To represent web as: “ the web of real world object rather than only web of documents.” Quratulain Rajput

  3. RDF • Construction of URI Scheme:[//authority]path[?query][#fragment] [Note: path and fragment are optional.] http://www.iba.edu.pk/ http://cs.iba.edu.pk/faculty.html#sghani https://www.google.com.pk/search?q=textmining+the+quran&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a Quratulain Rajput

  4. RDF <rdf:Descriptionrdf:about=“http://ww.iba.edu.pk/asif”> <hasAge>40</hasAge> </rdf:Description> <rdf:Descriptionrdf:about=“http://ww.iba.edu.pk/asif”> <writeBook> <rdf:Descriptionrdf:about=“http://www.semantic-web- book.org/”> </rdf:Description> </writeBook> </rdf:Description> Quratulain Rajput

  5. XML namespaces and RDF • Draw for the following description. Quratulain Rajput

  6. RDF Representation • Draw Graphs, are these represent same meaning? Quratulain Rajput

  7. IRI • IRI (International Resource Identifier) is extended URI by allowing non-Latin (Chinese, Urdu, Arabic) characters. Quratulain Rajput

  8. Shorter URI • xmlns can only used with xml tags and with attribute but not as value of attribute (e.g allowed with rdf:about, rdf:resource). • Use of Xml:base with rdf:about <xml version=“1.0“ encoding=“utf-8“> <rdf:RDFxmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#“ xmlns:data=“http://iba.edu.pk/research#“ xml:base=“http://iba.edu.pk/Faculty“> <rdf:Descriptionrdf:about=“#Quratulain“data:teaches=“Semantic Web“> <data:writesWiki rdf:resource=“http://cse661semanticwebspring2013.wikispaces.com/“/> </rdf:Description> </rdf:RDF> Quratulain Rajput

  9. Shorter URI • Use of xml:base with rdf:ID (used only once) <xml version=“1.0“ encoding=“utf-8“> <rdf:RDFxmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#“ xmlns:data=“http://iba.edu.pk/research#“ xml:base=“http://iba.edu.pk/Faculty“> <rdf:Descriptionrdf:ID=“Quratulain“data:teaches=“Semantic Web“> <data:writesWiki rdf:resource=“http://cse661semanticwebspring2013.wikispaces.com/“/> </rdf:Description> </rdf:RDF> Quratulain Rajput

  10. Rdf:Datatypes • RDF describe data values by means of literals. • E.G string, number etc. • Each datatype is uniquely identified by a URI. • RDF use the xml-schema for datatype description. <xml version=“1.0“ encoding=“utf-8“> <rdf:RDFxmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#“ xmlns:course=“http://iba.edu.pk/MS/courses#“ > <rdf:Descriptionrdf:about=“http://iba.edu.pk/MS/CSE661“> <course:Namerdf:datatype=“http://www.w3c.org/2001/XMLSchema#string“> Semantic Web </course:Name> <course:credit rdf:datatype= “http://www.w3c.org/2001/XMLSchema#integer“> 3 </course:credit> </rdf:Description></rdf:RDF> Quratulain Rajput

  11. <xml version=“1.0“ encoding=“utf-8“> <rdf:RDFxmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#“ xmlns:course=“http://iba.edu.pk/MS/course#“ > <rdf:Descriptionrdf:about=“http://iba.edu.pk/MS/CSE661“> <course:Namerdf:datatype=“http://www.w3c.org/2001/XMLSchema#string“> Semantic Web </course:Name> <course:credit rdf:datatype= “http://www.w3c.org/2001/XMLSchema#integer“> 3 </course:credit> </rdf:Description></rdf:RDF> http://iba.edu.pk/MS/course#Name Semantic Web http://iba.edu.pk/MS/CSE661 4 http://iba.edu.pk/MS/course#credit Quratulain Rajput

  12. Multiple values Relation • Problem: which height belong to which member. • Solution: A node with no unique name is called blank node. • It use to aggregate facts in form of list. Asif saad http://www.footballpakistan.com/hasMember http://www.footballpakistan.com/hasMember http://www.footballpakistan.com/team http://www.footballpakistan.com/hasHeight http://www.footballpakistan.com/hasHeight 6.5ft 6 ft Quratulain Rajput

  13. Blank Node • Blank node cannot be addressed globally with URI. 6 ft saad http://www.footballpakistan.com/hasName http://www.footballpakistan.com/hasHeight http://www.footballpakistan.com/hasMember http://www.footballpakistan.com/hasHeight http://www.footballpakistan.com/team 6.5ft http://www.footballpakistan.com/hasMember Asif http://www.footballpakistan.com/hasName Quratulain Rajput Quratulain Rajput 13

  14. Blank Node <rdf:Description rdf:about=“http://footballpakistan.com/team#Mem“> <te:hasMemberrdf:parseType=“Resource“/> <te:hasName>Asif</te:hasName> <te:hasHeight>6.5</te:hasHeight> </te:hasMember> </rdf:Description> Quratulain Rajput

  15. Blank node with name • Blank node can be assign name if needed. <rdf:Description rdf:about=“http://footballpakistan.com/team#Mem“> <te:hasMemberrdf:nodeID=“M1”/> </rdf:Description> <rdf:Descriptionrdf:nodeID=“M1”> <te:hasName>Asif</te:hasName> <te:hasHeight>6.5</te:hasHeight> </te:hasMember> </rdf:Description> Quratulain Rajput

  16. Container Elements • Represents a group of resources or literals E.g., we may wish to talk about the courses given by a particular lecturer • The content of container elements are named rdf:_1, rdf:_2, etc. or alternatively rdf:li Quratulain

  17. Three Types of Container Elements • rdf:Bag an unordered container, allowing multiple occurrences • E.g. members of the faculty board, documents in a folder • rdf:Seq an ordered container, which may contain multiple occurrences • E.g. modules of a course, items on an agenda, an alphabetized list of staff members (order is imposed) • rdf:Alt a set of alternatives • E.g. the document home and mirrors, translations of a document in various languages Quratulain

  18. Example for a Bag <uni:lecturerrdf:ID= "FAC949"uni:name="Atif" uni:title="Professor"> <uni:coursesTaught> <rdf:Bag> <rdf:_1 rdf:resource="#CSE101"/> <rdf:_2 rdf:resource="#CSE206"/> </rdf:Bag> </uni:coursesTaught> </uni:lecturer> Quratulain

  19. Example for Alternative <uni:courserdf:ID=“CSE206" uni:courseName=“Data Structures"> <uni:lecturer> <rdf:Alt> <rdf:lirdf:resource="#FAC949"/> <rdf:lirdf:resource="#FAC318"/> </rdf:Alt> </uni:lecturer> </uni:course> Quratulain

  20. Question Describe it using container? Referee(X,Y,Z) : X is the referee in a chess game between players Y and Z Quratulain

  21. RDF Collections • A limitation of these containers is that there is no way to close them • “these are all the members of the container” • RDF provides support for describing groups containing only the specified members, in the form of RDF collections • list structure in the RDF graph • constructed using a predefined collection vocabulary: rdf:List,rdf:first,rdf:restand rdf:nil Quratulain

  22. Reification • In RDF it is possible to make statement about statement such as Ahmed belief that Hassan is the creator of the web page http://www.xyz.com How would you do this?try. RDF allow this using reification mechanism. Quratulain

  23. Reification <rdf:Description rdf:about=“#NYT”> <claims> <rdf:Description rdf:about=“#pers05”> <authorOf>ISBN...</authorOf> </rdf:Description> </claims> </rdf:Description> Author-of pers05 ISBN... • Any statement can be an object graphs can be nested - reification claims NYT Quratulain

  24. Reification <rdf:Statementrdf:about=“Statementaboutpers05”> <rdf:subjectrdf:resource=“#pers05”/> <rdf:predicaterdf:resource=“#authorOf”/> <rdf:object>ISBN</rdf:object> </rdf:Statement> <rdf:Descriptionrdf:about=“#NYT”> <claims> <rdf:Descriptionrdf:resource=“#Statementaboutpers05”/> </claims> </rdf:Description> <rdf:Descriptionrdf:about=“#NYT”> <claims> <rdf:Descriptionrdf:about=“#pers05”> <authorOf>ISBN...</authorOf> </rdf:Description> </claims> </rdf:Description> • RDF turns a statement into resource. Quratulain

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