Defining cardinality for a RDF statement.

Question

Im having a problem with RDF. I have a couple of triples defined as :

<User rdf:about="#T">
 <hasName rdf:datatype="http://www.w3.org/2001/XMLSchema#string"&gt;T&lt;/hasName&gt;
 <hasFavourite rdf:resource="#x"/>
 <hasFavourite rdf:resource="#y"/>
</User>

Im wanting to add to the (user, hasFavourite, x) and (user, hasFavourite, y) triples as i need to associate an integer with them. Im a bit unsure of how to add an integer to a triple. Im sure this must be simple but im just getting my head around RDF so any help is appreciated.

Thanks Ally

Answer 1

I'm not entirely clear what you want to model here; that the User resource has triples with integer values or X and Y resources have integer values. I'll assume the latter since it's more complex.

<?xml version="1.0" encoding="utf-8"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns="http://example.org/ns#"&gt;
<User rdf:about="#T">
 <hasName rdf:datatype="http://www.w3.org/2001/XMLSchema#string"&gt;T&lt;/hasName&gt;
 <hasFavourite rdf:resource="#x"/>
 <hasFavourite rdf:resource="#y"/>
</User>
 <hasFavourite rdf:about="#x">
   <integerThatMeansSomething rdf:datatype="http://www.w3.org/2001/XMLSchema#integer"&gt;10&lt;/integerThatMeansSomething&gt;
 </hasFavourite>
 <hasFavourite rdf:about="#y">
   <integerThatMeansSomething rdf:datatype="http://www.w3.org/2001/XMLSchema#integer"&gt;20&lt;/integerThatMeansSomething&gt;
 </hasFavourite>
</rdf:RDF>

This is slightly easier to read in Turtle: (converted via rapper -q -o turtle foo.rdf 'http://example.org/ns#' from my Raptor software)

@base <http://example.org/ns#&gt; .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#&gt; .
@prefix : <> .

:T
    :hasFavourite :x, :y ;
    :hasName "T"^^<http://www.w3.org/2001/XMLSchema#string&gt; ;
    a :User .

:x
    :integerThatMeansSomething 10 ;
    a :hasFavourite .

:y
    :integerThatMeansSomething 20 ;
    a :hasFavourite .

Disclaimer: I edited rdf/xml, invented Turtle and wrote the software above!

Reading above like: "T is a User, has two favourites x and y and a string name. X is a favourite and has an integer property with value 10." etc. for Y.

If it was the former, the rdf/xml is simpler:

<User rdf:about="#T">
 <hasName rdf:datatype="http://www.w3.org/2001/XMLSchema#string"&gt;T&lt;/hasName&gt;
 <hasFavourite rdf:datatype="http://www.w3.org/2001/XMLSchema#integer"&gt;10&lt;/hasFavourite&gt;
 <hasFavourite rdf:datatype="http://www.w3.org/2001/XMLSchema#integer"&gt;20&lt;/hasFavourite&gt;
</User>

Answer 2

So if I'm reading the question and your comment on dajobe's post correctly you probably want something like this (again in Turtle notation since it's so much more readable):

@base <http://example.org/ns#&gt; .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#&gt; .
@prefix : <> .

:T
    :hasFavourite :fave1, :fave2 ;
    :hasName "T" ;
    a :User .

:fave1 a :Favourite ;
       :band :x ;
       :playCount 10 .

:fave2 a :Favourite ;
       :band :y ;
       :playCount 4 .

:x a :Band ;
   :hasName "Band 1" .

:y a :Band ;
   :hasName "Band 2" .

So this allows you to keep play counts for each users favourites individually and each Band may be chosen as a favourite by different users by creating new Favourites as required.

I could of course be completely wrong of course and this may be nothing like what you actually want!