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.
 The period at the end – very important
Object Can Be Literal
<#pat> <#knows> <#jo> .
<#pat> <#age> "24" .
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Note: noun form "age" preferred to the
verb style "knows" for predicates
Alternative Forms
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<#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)
Comma and Semicolon
<#pat> <#child> <#al>, <#chaz>, <#mo> ;
<#age> "24" ;
<#eyecolor> "blue" .
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Comma: delimits multiple objects for same
subject & predicate
Semicolon: delimits multiple predicates for
same subject.
Aim? Easy scribbling of data.
Data …e.g. a table
age
eyecolor
pat
24
blue
al
3
green
jo
5
green
<#pat> <#age> "24"; <#eyecolor> "blue" .
<#al> <#age> "3"; <#eyecolor> "green" .
<#jo> <#age> "5"; <#eyecolor> "green" .
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" ].
Sharing Concepts
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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
Local Concept
<> <#title> "A simple example of N3".

Who or what knows what <#title> is?
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 "#"
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#> .
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and also
@prefix : <#> .
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e.g.
:pat :child [ :age "4" ] , [ :age "3" ].
RDF Conversion
<RDF xmlns="http://www.w3.org/1999/02/22-rdfsyntax-ns#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdfsyntax-s#"
xmlns:rdfs="http://www.w3.org/2000/01/rdfschema#"
xmlns:owl="http://www.w3.org/2002/07/owl#" />
Making Vocabularies
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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
Cont.
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Equivalent:
:Person rdf:type rdfs:Class
:Person a rdfs:Class.
Which we could use with data:
:Pat a :Person.
Classes
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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
Examples: class and property
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: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
Best Practice
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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 .
Examples
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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
Pat is a human with the names "Pat
Smith" and "Patrick Smith". Pat has a
pet, a dog, with the name "Rover".
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/friendsvocab#> .
:pat a bio:Human;
per:name "Pat Smith",
"Patrick Smith";
per: pet [
a bio:Dog;
per:name "Rover" ] .
Directed Labeled Graph
RDF Translation
<rdf:RDF
xmlns="http://www.w3.org/2000/10/swap/test/demo1/abo
ut-pat#"
xmlns:bio="http://www.w3.org/2000/10/swap/test/demo1/
biology#"
xmlns:per="http://www.w3.org/2000/10/swap/test/demo1/f
riends-vocab#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntaxns#">
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>
END