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RDF using N3

RDF using N3. Subject, Verb and Object. All knowledge is just a set of statements <#pat> <#knows> <#jo> . Everything is identified by URI Here a local URI but could point to ANY document Verb known as predicate in the statement and represents a Property .

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RDF using N3

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  1. RDF using N3

  2. Subject, Verb and Object All knowledge is just a set of statements <#pat> <#knows> <#jo> . • Everything is identified by URI • Here a local URI but could point to ANY document • Verb known as predicate in the statement and represents a Property. • The period at the end – very important

  3. Object Can Be Literal <#pat> <#knows> <#jo> . <#pat> <#age> "24" . • Note: noun form "age" preferred to the verb style "knows" for predicates

  4. Alternative Forms <#pat> has <#child> <#al> . • Just to make reading easier; no meaning <#al> is <#child> of <#pat> . • is and of reverse the direction • Saves having inverse relationships for everything (eg parent)

  5. Comma and Semicolon <#pat> <#child> <#al>, <#chaz>, <#mo> ; <#age> "24" ; <#eyecolor> "blue" . • Comma: delimits multiple objects for same subject & predicate • Semicolon: delimits multiple predicates for same subject. • Aim? Easy scribbling of data.

  6. Data …e.g. a table <#pat> <#age> "24"; <#eyecolor> "blue" . <#al> <#age> "3"; <#eyecolor> "green" . <#jo> <#age> "5"; <#eyecolor> "green" .

  7. Unnamed Things: Square Brackets <#pat> <#child> [ <#age> "4" ] , [ <#age> "3" ]. • Words used as IDs have no actual meaning • Unnamed nodes can't be used elsewhere • ID things are names; make the name explicit [ <#name> "Pat"; <#age> "24"; <#eyecolor> "blue" ]. [ <#name> "Al" ; <#age> "3"; <#eyecolor> "green" ]. [ <#name> "Jo" ; <#age> "5"; <#eyecolor> "green" ].

  8. Sharing Concepts • Using the same URIs is effort but valuable • For anything -- including predicates • URIs tend to be long so we use namespaces • Writing authoritative documents about shared concepts is useful

  9. Local Concept <> <#title> "A simple example of N3". • Who or what knows what <#title> is?

  10. Shared Concept <http://purl.org/dc/elements/1.1/title> "Primer - Getting into the Semantic Web and RDF using N3". @prefix dc: <http://purl.org/dc/elements/1.1/> . <> dc:title "Primer - Getting into the Semantic Web and RDF using N3". • No <> used when prefixed identifier • Typically prefix stands for everything up to including a "#"

  11. Assumed Prefixes • In this tutorial: @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . @prefix owl: <http://www.w3.org/2002/07/owl#> . • and also @prefix : <#> . • e.g. :pat :child [ :age "4" ] , [ :age "3" ].

  12. RDF Conversion <RDFxmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-s#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:owl="http://www.w3.org/2002/07/owl#" />

  13. Making Vocabularies • A set of shared concepts • Properties are things to use as predicates (verbs) • Classes can be the type of an object • rdf:type is just a property, abbreviated to "a" in N3

  14. Cont. • Equivalent: :Person rdf:type rdfs:Class :Person a rdfs:Class. • Which we could use with data: :Pat a :Person.

  15. Classes • An object can be in many classes • Classes can have many superclasses • You can never know all the classes an object is in • These are classes of real things, not OO classes

  16. Examples: class and property :Woman a rdfs:Class; rdfs:subClassOf :Person . :sister a rdf:Property. • Something about the Property :sister:: :sister rdfs:domain :Person; rdfs:range :Woman. • Use: • :Pat :sister :Jo. • Class ids start with capital, Propoerty ids with lowercase

  17. Best Practice • Use other people's terms when you can • Use your own when you need to • Be prepared to declare them equivalent later • = in N3 is short for owl:equivalentTo :Woman = foo:FemaleAdult . :title a rdf:Property; = dc:title .

  18. Examples • English (Very Informal): There is person, Pat, known as "Pat Smith" and "Patrick Smith". Pat has a pet dog named "Rover". • English Hypertext (Informal): • Ambiguity of terms is removed by links Patis ahuman with the names "Pat Smith" and "Patrick Smith". Pat has a pet, adog, with the name "Rover".

  19. N3 @prefix : <http://www.w3.org/2000/10/swap/test/demo1/about-pat#> . @prefix bio: <http://www.w3.org/2000/10/swap/test/demo1/biology#> . @prefix per: <http://www.w3.org/2000/10/swap/test/demo1/friends-vocab#> . :pat a bio:Human; per:name "Pat Smith", "Patrick Smith"; per: pet [ a bio:Dog; per:name "Rover" ] .

  20. Directed Labeled Graph

  21. RDF Translation <rdf:RDF xmlns="http://www.w3.org/2000/10/swap/test/demo1/about-pat#" xmlns:bio="http://www.w3.org/2000/10/swap/test/demo1/biology#" xmlns:per="http://www.w3.org/2000/10/swap/test/demo1/friends-vocab#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">

  22. Cont. <bio:Human rdf:about="#pat"> <per:name>Pat Smith</per:name> <per:name>Patrick Smith</per:name> <per:pet> <bio:Dog> <per:name>Rover</per:name> </bio:Dog> </per:pet> </bio:Human> </rdf:RDF>

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