Post on 06-Feb-2016
description
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" .
Note: noun form "age" preferred to the verb style "knows" for predicates
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)
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.
Data …e.g. a table
<#pat> <#age> "24"; <#eyecolor> "blue" .
<#al> <#age> "3"; <#eyecolor> "green" . <#jo> <#age> "5"; <#eyecolor> "green" .
age eyecolor
pat 24 blue
al 3 green
jo 5 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 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#> . and also@prefix : <#> . e.g.
:pat :child [ :age "4" ] , [ :age "3" ].
RDF Conversion
<RDF xmlns="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#" />
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
Cont. Equivalent:
:Person rdf:type rdfs:Class :Person a rdfs:Class.
Which we could use with data::Pat a :Person.
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
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
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 .
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 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/friends-vocab#> .
: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/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#">
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