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Re: modeling document classes with OWL

From: Dan Brickley <danbri@w3.org>
Date: Sun, 3 Apr 2005 15:35:34 -0400
To: algermissen@acm.org
Cc: www-rdf-interest@w3.org
Message-ID: <20050403193534.GB19248@homer.w3.org>

* Jan Algermissen <jalgermissen@topicmapping.com> [2005-04-03 21:14+0200]
> 
> Hi,
> 
> I want to use OWL class descriptions to define classes of documents but 
> I can't find out, how to describe (for example) that an 'Article' has a 
> sequence of sections.
> 
> Here is an example:
> 
> First I describe that 'Articles have exactly one dc:title and one 
> dc:creator'
> 
> <owl:Class rdf:ID="Article">
>  <owl:equivalentClass>
>    <owl:Class>
>      <owl:intersectionOf rdf:parseType="Collection">
>        <owl:Restriction> 
>          <owl:onProperty rdf:resource="&dc;title" />
>          <owl:cardinality
>            rdf:datatype="&xsd;nonNegativeInteger">1</owl:cardinality>
>        </owl:Restriction>
>        <owl:Restriction>
>          <owl:onProperty rdf:resource="&dc;creator" />
>          <owl:cardinality  
>            rdf:datatype="&xsd;nonNegativeInteger">1</owl:cardinality>
>        </owl:Restriction>
>      </owl:intersectionOf>  
>    </owl:Class>
>  </owl:equivalentClass>
> </owl:Class>
> 
> (That is the (a) way to do that I hope).
> 
> 
> I'd add other required or optional properties (such as teaser, copyright 
> information, etc.) in the same way. 
> I (think) I can say that an Article has 0...N sections with 
> owl:minCardinality and owl:maxCardinality, but I want them to be ordered 
> (of course). 
> An instance of the Article class I have in mind would need to 'have' an 
> rdf:Seq containing the sections, I think (correct?). Could anyone help me 
> with the question of how I say that in OWL?
 
A brief comment. I think the core issue here is two subtle senses of
'have'. The thing in the world, ie. the article itself, might have 
certain things true of it. And then some specific RDF instance data
might carry RDF statements describing some or all of those things. OWL 
talks in terms of constraints regarding things in the world, rather than 
constraints on the content of RDF documents about those things. XML by 
contrast is all about types of document (and in RDF/XML, about types 
of description). So I think you need to know whether your rules are 
to be rules about the properties of 'Articles' in the abstract, or about
the characteristics of specific RDF/XML descriptions of them. 

Hmm that's maybe a bit confusing. I'll have a think about how to
rephrase...

hope it might help anyway,

Dan


> 
> Note:
> 
> - I know that XML would be my friend here, but I do want to use RDF
> - I also do not want to use XML semantics (like the infoset RDF namespace) 
> to express the desired content model
> 
> Many! thanks in advance for any clarification of this issue.
> 
> 
> Jan
> 
> 
> 
> -- 
> Jan Algermissen
> Consultant & Programmer
> http://jalgermissen.com
> 
> 
Received on Sunday, 3 April 2005 19:36:18 GMT

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