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Re: [Fwd: Re: Serialization skos:Concept vs owl:Thing vs rdf..]

From: Simon Jupp <simon.jupp@manchester.ac.uk>
Date: Wed, 16 Sep 2009 14:23:42 +0100
Cc: <steve.richard@azgs.az.gov>, "'Guillame Duclaux'" <Guillaume.Duclaux@csiro.au>, <public-esw-thes@w3.org>
Message-Id: <8CA956DC-21AF-43D8-B5A5-93909C0ED816@manchester.ac.uk>
To: Simon Cox <simon.cox@jrc.ec.europa.eu>

Protege and the SKOSEd plugin don't "promote" SKOS to OWL. The SKOS  
concepts and relationships are defined as an OWL vocabulary. When you
load SKOS files into Protege you simply get a representation of what  
was asserted (which may include additional triples that are inferred,  
such as those asserting rdf:type owl:Thing).

Any SKOS exported from Protege as RDF/XML is likely to contain these  
triples that use the OWL vocabulary, but why should this matter to any
tool that consumes RDF? Any constructs they don't handle should just  
get ignored. If a service can't handle the RDF (and SKOS) generated by
Protege then I would be interested to know why, it is after all just  
RDF, nothing special about it because it has some additional OWL  
vocabulary in there.

On the point of consistent serialisation, I can sort of see a case for  
being consistent, but RDF can be serialised to XML in multiple ways,  
so I wouldn't expect any tool to rely on particular style. SKOS was  
designed to be flexible and extensible, this means it's quite hard to  
define what pure SKOS is, any standalone SKOS editor will have limits  
on what can be expressed. To provide ultimate flexibility you would  
need an OWL full or RDF editor, but this is possibly the wrong level  
of abstraction for most people working with SKOS.

Cheers
Simon

On 15 Sep 2009, at 07:51, Simon Cox wrote:

> I guess Protege uses OWL as its internal model, so this kind of  
> behaviour, though annoying, is to be expected.
>
> What this points to is that the world needs a RDF or SKOS editor  
> that does not gratuitously promote everything up to OWL.
> Promoting everything to OWL kinda misses the point of having SKOS,  
> which is explicitly for applications that do not need to go all the  
> way to OWL.
>
> I'll forward this to the W3C SKOS list, since it is a follow-up to  
> the discussion we triggered in June.
>
> --------------------------------------------------------
> Simon Cox
>
> European Commission, Joint Research Centre
> Institute for Environment and Sustainability
> Spatial Data Infrastructures Unit, TP 262
> Via E. Fermi, 2749, I-21027 Ispra (VA), Italy
> Tel: +39 0332 78 3652
> Fax: +39 0332 78 6325
> mailto:simon.cox@jrc.ec.europa.eu
> http://ies.jrc.ec.europa.eu/simon-cox
>
> SDI Unit: http://sdi.jrc.ec.europa.eu/
> IES Institute: http://ies.jrc.ec.europa.eu/
> JRC: http://www.jrc.ec.europa.eu/
> --------------------------------------------------------
>
>
> From: Stephen M Richard [mailto:steve.richard@azgs.az.gov]
> Sent: Monday, 14 September 2009 19:30
> To: Simon Cox; Guillame Duclaux
> Subject: [Fwd: Re: Serialization skos:Concept vs owl:Thing vs rdf..]
>
> Simon, Gilly--
> I noticed that Protege is randomly encoding as either skos:concept  
> or owl:thing with rdf:type=&skos;Concept. I posted a question on the  
> skos-dev list, here's simon's response (full discussion at http://groups.google.com/group/skos-dev/browse_thread/thread/1b37afd209da564d?hl=en) 
> . Someone posted an xslt to get rid of the owl:things. Basically its  
> a Protege issue--what I started with is all skos.
>
> steve
>
>
>
> -------- Original Message --------
> Subject:	Re: Serialization skos:Concept vs owl:Thing vs rdf..
> Date:	Wed, 19 Aug 2009 03:48:45 -0700 (PDT)
> From:	Simon Jupp <simon.jupp@gmail.com>
> Reply-To:	skos-dev@googlegroups.com
> To:	skos-dev <skos-dev@googlegroups.com>
> References:	<d8e4f408-dc49-49e9-be28-e2c4ad9c11cf@i18g2000pro.googlegroups.com 
> >
>
>
> I don't see why it matters, when you say unclean, do you mean for the
> human eye? Can you give an example where this might be a problem? It
> is a little redundant, but it shouldn't be a problem for any tools
> that consume RDF/XML.
>
> Looking at your files I do see that the RDF/XML rendering seems to be
> a little inconsistent. I will speak to the OWL API developer to find
> out why this is.
>
> Cheers
> Simon
>
> On Aug 19, 2:26 am, smrAZGS <steve.rich...@azgs.az.gov> wrote:
> > I've noticed the same issue. Converting to OWL doesn't seem like a
> > solution, since the point of a SKOS encoding is to use elements in
> > the  SKOS namespace. I recognize that skos:concept and owl:thing  
> with
> > rdf:type=&skos;Concept are logically equivalent, but isn't is
> > problematic if you're trying to automate use of the document if the
> > encoding might use one of two equivalent syntax approaches in the  
> same
> > document- it just doesn't seem 'clean'. If a document is supposed to
> > be a SKOS encoding it seems like there should be some way to ensure
> > that it uses SKOS elements, not owl?
> >
> > steve
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>
> -- 
> Stephen M. Richard
> Section Chief, Geoinformatics
> Arizona Geological Survey
> 416 W. Congress St., #100
> Tucson, Arizona, 85701 USA
>
> Phone:
> Office: (520) 209-4127
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>
> email: steve.richard@azgs.az.gov



Simon Jupp
simon.jupp@manchester.ac.uk
http://www.cs.man.ac.uk/~sjupp/
Received on Wednesday, 16 September 2009 13:24:23 GMT

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