The N3 Cheat Sheet

del.icio.us Tags: semantic web , SemanticWeb , N3 , turtle , RDF , quick reference , cheat sheet , quickref

When I was getting to know RDF, I put together a short quickref guide of the N3 Notation to help remind me while I wrote ontologies. I’ve found many of the tools such as Protege awkward or cumbersome, so I tend to use a text editor. Needless to say there’s no integrated to help, so I used the following table to help me. I hope it helps you get started. I know it is pretty rough, and in some cases I’m using namespaces from all over the place. I will tidy it up soon. I promise.

You might also want to take a look a the W3C’s N3 Primer, the Specification and the Resources link page.

Task	Example and Commentary
Ontologies - importing	<> a daml:Ontology; daml:comment "An example ontology"; daml:imports <http://www.daml.org/2000/10/daml-ont>; daml:versionInfo "$Id: daml-ex.n3,v 1.5 2001/05/21 03:11:59 timbl Exp $"
Ontologies - namespaces	@prefix dc: <http://purl.org/dc/elements/1.1/> .
Ontologies - this document	<> <#title> "A simple example of N3". the empty brackets indicate the current document
Basics - triples	<#subject> <#predicate> <#object> . the fullstop matters
Basics - literals	<#subject> <#predicate> 1524 . on object only
Basics - default namespace	@prefix : <#> . now you can refer to things as :Foo rather than <#Foo>
Syntax - comments	# this is a comment
Syntax - chaining	:MyCar :make :Hyundai; :model :SantaFe .
Syntax - multiline literals	"""something over a few lines"""
Syntax - blank nodes	<#pat> <#child> [ <#age> 4] , [ <#age> 3]. creates an anonymous subject for the predicate and object. i.e. some child of age 4
Syntax - string escaping	Goto here It follows the rules laid down by Python.
Syntax - equivalence	:Woman = foo:FemaleAdult . Title a rdf:Property; = dc:title .
Syntax - going down paths	:joe!fam:mother!loc:office!loc:zip Joe’s mother’s office’s zipcode
Syntax - going up paths	:joe!fam:mother^fam:mother Anyone whose mother is Joe’s mother.
Syntax - formulae	{ [ x:firstname "Ora" ] dc:wrote [ dc:title "Moby Dick" ] } a n3:falsehood . the expression in {braces} is false - that there is nothing called Ora which wrote anything titled "Moby Dick".
Syntax - lists	(:Tom :Dick :Harry)
Syntax - comments	:Person a daml:Class; daml:comment "every person is a man or a woman"; daml:disjointUnionOf ( :Man :Woman ).
Syntax - enumerations	:Height a daml:Class; daml:oneOf ( :short :medium :tall ) .
Classes - declarations	:Person a rdfs:Class.
Classes - inheritance	:Woman a rdfs:Class; rdfs:subClassOf :Person .
Classes - multiple inheritance	:TallMan a daml:Class; daml:intersectionOf ( :TallThing :Man ) .
Classes - disjoint union	:Person a daml:Class; daml:comment "every person is a man or a woman"; daml:disjointUnionOf ( :Man :Woman ).
Classes - complement	:Car a daml:Class; daml:comment "no car is a person"; daml:subClassOf [ a daml:Class; daml:complementOf :Person ] .
Properties - declaration	:sister a rdf:Property. sister rdfs:domain :Person; rdfs:range :Woman.
Properties - transitive	:descendant a daml:TransitiveProperty .
Properties - restrictions	:TallThing a daml:Class; daml:restrictedBy [ a daml:Restriction; daml:onProperty :height; daml:toValue :tall ] .
Properties - cardinality	:father a daml:Property; daml:cardinality "1"; daml:range :Man; daml:subProperty :parent .
Properties - max and min cardinalities	:wheels a daml:Property; daml:minCardinality "1" . daml:maxCardinality "3" .
Properties - subproperties	:father a daml:Property; daml:cardinality "1"; daml:range :Man; daml:subProperty :parent . redefines the range of the property
Properties - inverse	:child a daml:Property; daml:inverseOf :parent .
Rules - implication	Foo log:implies :Bar Foo => :Bar
Rules - quantifiers (for each)	@forSome <#g>. The universal quantifier (∀g) - this is global to the document
Rules - quantifiers (for some)	@forSome <#g>. the existential quantifier (∃g) - also global to the document
Rules - free variables	{?P @has owl:inverseOf ?Q. ?S ?P ?O} => {?O ?Q ?S}. ?P, ?Q, ?S, and ?O are all free variables. these variables are local to the clause only