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RDF Examples

A quick guide to RDF syntax, including examples and guidelines for using RDF Property Elements, Abbreviated RDF Syntax, and RDF Containers.

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RDF Examples

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  1. RDF Examples • Quick Guide to RDF Syntax • Nancy Ide • Vassar College • Eurolan 2003 The Semantic Web and Language Technology

  2. The RDF Description Element • Attributes • about • refers to a URI of an existing resource • ID • signals the creation of a new resource <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <rdf:Description about="http://www.cs.vassar.edu/~ide/"> . . . </rdf:Description> <rdf:Description rdf:ID="Nancy Ide"> . . . </rdf:Description> </rdf:RDF>

  3. RDF Property Elements • Property names must be associated with a schema • Qualify property names with a namespace prefix • Production propertyElt: <PropertyName> Value </PropertyName> • Value = Description element or String <?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/"> <rdf:Description about="http://www.cs.vassar.edu/~ide/rdf/"> <dc:creator>Nancy Ide</dc:creator> </rdf:Description> </rdf:RDF>

  4. Using Abbreviated RDF Syntax Property elements converted to attributes <?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/"> <rdf:Description about="http://www.cs.vassar.edu/~ide/ESA.pdf"> <dc:creator>Nancy Ide</dc:creator> <dc:title>Encoding Syntactic Annotation</dc:title> <dc:date>2001-04-10</dc:date> </rdf:Description> </rdf:RDF> <?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/"> <rdf:Description about="http://www.cs.vassar.edu/~ide/ESA.pdf" dc:creator="Nancy Ide" dc:title="Encoding Syntactic Annotation" dc:date="2001-04-10"/> </rdf:RDF>

  5. Using Abbreviated RDF Syntax • New fact:   http://www.cs.vassar.edu/~ide is an instance of a WebPage • rdf:type element adds this new fact • value of the rdf:type can be used directly as element name <?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/"> <rdf:Description about="http://www.cs.vassar.edu/~ide"> <rdf:type rdf:resource="http://www.schemas.org/www/Webpage"/> <dc:creator>Nancy Ide</dc:creator> </rdf:Description> </rdf:RDF> <?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:s="http://www.schemas.org/www/"> <s:WebPage about="http://www.cs.vassar.edu/~ide"> <dc:creator>Nancy Ide</dc:creator> </s:WebPage> </rdf:RDF>

  6. RDF Containers • Bag • An unordered list of resources or literals • Sequence • An ordered list of resources or literals • Alternative • A list of resources or literals that represent alternatives for the value of a property

  7. Using the Bag Container • Statement: • The authors of the book 0201000237 are Alfred, John and Jeffrey <?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/"> <rdf:Description about="urn:ISBN:0-201-00023-7"> <dc:creator> <rdf:Bag> <rdf:li>Alfred</rdf:li> <rdf:li>John</rdf:li> <rdf:li>Jeffrey</rdf:li> </rdf:Bag> </dc:creator> </rdf:Description> </rdf:RDF>

  8. Using the Seq Container • Statement: • The students of the course csci-2962 in alphabetical order are • Elizabeth, George and John <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:s="http://www.schemas.org/Course/"> <rdf:Description about="http://www.cs.vassar.edu/courses/cs240"> <s:students> <rdf:Seq> <rdf:li rdf:resource="http://www.cs.vassar.edu/students/er"/> <rdf:li rdf:resource="http://www.cs.vassar.edu/students/gl"/> <rdf:li rdf:resource="http://www.cs.vassar.edu/students/js"/> </rdf:Seq> </s:students> </rdf:Description> </rdf:RDF>

  9. Using the Alt Container • Statement:   • The formats of the book 0201000237 are plain text, html • and postscript <?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/"> <rdf:Description about="urn:ISBN:0-201-00023-7"> <dc:format> <rdf:Alt> <rdf:li>text/html</rdf:li> <rdf:li>text/plain</rdf:li> <rdf:li>application/postscript</rdf:li> </rdf:Alt> </dc:format> </rdf:Description> </rdf:RDF>

  10. Making Statements about Containers <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:s="http://www.schemas.org/Course/" xmlns:dc="http://purl.org/dc/elements/1.1/"> <rdf:Description about="http://www.cs.vassar.edu/courses/cs240"> <s:homeworks> <rdf:Bag ID="pages"> <rdf:li rdf:resource="http://www.cs. vassar.edu/courses/cs240/hw1.html"> <rdf:li rdf:resource="http://www.cs. vassar.edu/courses/cs240/hw2.html"> </rdf:Bag> </s:homeworks> </rdf:Description> <rdf:Description about="#pages"> <dc:creator>Nancy Ide</dc:creator> </rdf:Description> </rdf:RDF>

  11. Making Statements about the Items in a Container <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:s="http://www.schemas.org/Course/" xmlns:dc="http://purl.org/dc/elements/1.1/"> <rdf:Description about="http://www.cs.vassar.edu/courses/cs240"> <s:homeworks> <rdf:Bag ID="pages"> <rdf:li rdf:resource="http://www.cs. vassar.edu/courses/cs240/hw1.html"> <rdf:li rdf:resource="http://www.cs. vassar.edu/courses/cs240/hw2.html"> </rdf:Bag> </s:homeworks> </rdf:Description> <rdf:Description aboutEach="#pages"> <dc:creator>Nancy Ide</dc:creator> </rdf:Description> </rdf:RDF>

  12. Non-Binary Relations • The RDF data model only supports binary relations (relations between two resources) • Solution: Use an intermediate resource with additional properties <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:s="http://www.schemas.org/Units/"> <rdf:Description about="urn:ISBN:0-201-00023-7"> <s:price rdf:parseType="Resource"> <rdf:value>45.00</rdf:value> <s:units rdf:resource="http://www.schemas.org/Units/USdollar"/> </s:price> </rdf:Description> </rdf:RDF> Statement: The cost of the book 0201000237 is $45.00

  13. Reification • Making statements about statements • Classic example: “Dan Tufis says that Dan Cristea made the web page http://www.infoiasi.ro/~cristea.” asserts Dan Tufis Dan Cristea made http://www.infoiasi.ro/~cristea Simple solution: Put an rdf:ID attribute on the property element. By default, anything with an rdf:ID is an instance of RDF:Statement

  14. The parseType attribute • Use attribute parseType="Resource"on an RDF/XML element when there is an rdf:Description (or its equivalent) as a child element • Use attribute parseType=”Literal” on an RDF/XML element when the content is not to be parsed by the RDF parser <rdf:Description about="urn:ISBN:0-201-00023-7"> <s:price rdf:parseType="Resource"> <rdf:value>45.00</rdf:value> <s:units rdf:resource="http://www.schemas.org/Units/USdollar"/> </s:price> </rdf:Description> <dc:title rdf:parseType="Literal"> Solving <mrow> <mrow><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>1</mn></mrow> <mo>=</mo><mn>0</mn> </mrow> </dc:title>

  15. Exercise • Get your hands dirty with some real RDF... • Create an RDF schema for EAGLES morpho-syntactic categories • Extend to your own language, using the EAGLES specifications • Tag some text? • Use Protoge, a simple RDF editor, or a plain text editor

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