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Re: abbreviated RDF/XML was Re: Why does OWL have an XML presentation syntax?

From: Jonathan Borden <jonathan@openhealth.org>
Date: Mon, 08 Sep 2003 16:32:19 -0400
Message-ID: <3F5CE753.9050402@openhealth.org>
To: Matt Halstead <matt.halstead@auckland.ac.nz>
Cc: "Www-Rdf-Interest@W3. Org" <www-rdf-interest@w3.org>

Matt Halstead wrote:

> I certainly wasn’t very clear in my first email, especially the title.
> ...
> I think my problem comes down to understanding the value of 
> abbreviated forms of RDF/XML in documents based on extensions of RDF, 
> such as OWL. One problem is that there doesn’t seem to be a way to 
> deconstruct an OWL RDF/XML document into triples and put it back 
> together the way it was. While there is no loss in the interpretation 
> of the RDF graph alternative forms have, an IDE could end up showing a 
> different structure than was originally made.

I guess that would only be a problem if the IDE depends on the RDF/XML 
_as_ XML i.e. the ontology document is processed as XML rather than as 
triples. But tools developers do have issues with this, particularly if 
the tools wish to employ software that understands XML (there's lots of 
this around).

> The thread I mentioned above w.r.t the presentation syntax highlighted 
> the XML Schema problem of RDF/XML. This is part of what made me wonder 
> about why we write down RDF/XML constructs as is done in for example : 
> http://www.w3.org/TR/2003/WD-owl-ref-20030331/, you need to 
> deconstruct them into RDF/XML descriptions and then into triples to 
> process them. Example : i.e. why use abbreviated forms such as
>
> <owl:Human rdf:about="#William_Jefferson_Clinton">
> <owl:sameAs rdf:resource="#BillClinton"/>
> </owl:Human>
>
> instead of full RDF/XML descriptions when describing the syntax and 
> semantics of a language.

It's easier for people to write and read. An RDF application (which 
receives triples in anycase) could care less.

> ... What is pretty obvious to me is that the Schema can be thought of 
> as representing one possible abbreviated form of an RDF/XML 
> description. So if I instead interpret this language as an RDF based 
> language with its OWL Schema, then I can no longer say this XML Schema 
> they use to validate their models is complete – it may be sound, but 
> not complete. 

Yep.

> My next thought was that evolving the language within the confines of 
> this one XML Schema may be quite limiting, what we really want to do 
> is develop the language using an abstract syntax and semantics devoid 
> of XML limitations, and perhaps also limitations of using abbreviated 
> RDF/XML. 

RDF does not do anything to encourage you to constrain your documents 
using XML Schema.

> The conclusion was, why use the current XML form at all – i.e. it’s 
> simply an abbreviated RDF/XML representation. Hence my question about 
> why use abbreviated RDF/XML representations of OWL to explain OWL or 
> ontologies based on it.

In the specific case of OWL DL, the XML Schema provides syntactic 
validation for those folks who find syntactic validation useful. There 
are other uses such as software that might take an XML Schema and 
generate a document editor etc.

Jonathan
Received on Monday, 8 September 2003 16:32:30 GMT

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