W3C home > Mailing lists > Public > public-esw-thes@w3.org > September 2009

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

From: Simon Cox <simon.cox@jrc.ec.europa.eu>
Date: Wed, 16 Sep 2009 17:44:08 +0200
To: "'Simon Jupp'" <simon.jupp@manchester.ac.uk>
Cc: <steve.richard@azgs.az.gov>, "'Guillame Duclaux'" <Guillaume.Duclaux@csiro.au>, <public-esw-thes@w3.org>, <Jacqueline.Githaiga@csiro.au>
Message-ID: <B24174A74D1B4A06973B4EA856C70C0D@H07.jrc.it>
OK - I've just checked the SKOS Reference Recommendation, and see that the
relationship between SKOS and OWL is normative, so you are correct. 
I thought I recalled that SKOS was defined only in terms of RDF and RDFS,
with the links to OWL being non-normative, but maybe that was an earlier
version, or maybe I'm mistaken. 
 
Nevertheless, it does somewhat undermine the rationale for SKOS to convert
an ontology into OWL terminology when it had been formalized using only RDF
and SKOS. 
SKOS is intended to be a bridge for communities whose requirements do not
require OWL. 
I'm currently trying to convince a couple of communities (GeoSciML, GML)
that they should replace their bespoke vocabulary encodings with SKOS, since
SKOS appears to satisfy almost all the requirements from those communities. 
The target audience comes from an XML/XSD background, so there is an initial
challenge in getting over the RDF data-model humps (e.g. the fact that many
serializations are fully equivalent). 
This would be easier if the tools did not all-of-a-sudden munge the resource
types (even if the munging is correct according to RDF/OWL model). 
But perhaps I've just got to get over that. 
 
---
 
Meanwhile, the goal we are pursuing a 'simple' vocabulary service interface,
to complement the first S in SKOS. 
i.e. given a basic vocabulary model (SKOS), with a limited gamut of resource
and property types, to provide a small set of queries optimised to these. 
Our approach is to implement this on top of SPARQL, so the queries must be
expressible in SPARQL. 
 
I just checked the documentation prepared by my developer, mapping the
queries to SPARQL
(https://twiki.auscope.org/twiki/bin/view/Grid/VocabularyService02). 
It turns out that all the queries we have implemented so far rely only on
the SKOS properties, and are independent of the resource type. 
So it turns out that it does not matter to the query engine whether the
resources are skos:Concepts, rdf:Descriptions, owl:Things, or foo:Bars. 
It does matter to some XSLT processing tools that we have developed, but I
guess that points to the fact that SPARQL etc is the appropriate interface
for processing RDF, not XSLT. 
 
--------------------------------------------------------
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> mailto:simon.cox@jrc.ec.europa.eu 
 <http://ies.jrc.ec.europa.eu/simon-cox>
http://ies.jrc.ec.europa.eu/simon-cox 

SDI Unit:  <http://sdi.jrc.ec.europa.eu/> http://sdi.jrc.ec.europa.eu/ 
IES Institute:  <http://ies.jrc.ec.europa.eu/> http://ies.jrc.ec.europa.eu/ 
JRC:  <http://www.jrc.ec.europa.eu/> http://www.jrc.ec.europa.eu/

--------------------------------------------------------

 

  _____  

From: Simon Jupp [mailto:simon.jupp@manchester.ac.uk] 
Sent: Wednesday, 16 September 2009 15:24
To: Simon Cox
Cc: steve.richard@azgs.az.gov; 'Guillame Duclaux'; public-esw-thes@w3.org
Subject: Re: [Fwd: Re: Serialization skos:Concept vs owl:Thing vs rdf..]



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> mailto:simon.cox@jrc.ec.europa.eu 
 <http://ies.jrc.ec.europa.eu/simon-cox>
http://ies.jrc.ec.europa.eu/simon-cox 

SDI Unit:  <http://sdi.jrc.ec.europa.eu/> http://sdi.jrc.ec.europa.eu/ 
IES Institute:  <http://ies.jrc.ec.europa.eu/> http://ies.jrc.ec.europa.eu/ 
JRC:  <http://www.jrc.ec.europa.eu/> 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/1b37afd209da564
d?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  <mailto:simon.jupp@gmail.com> <simon.jupp@gmail.com>

Reply-To: 	skos-dev@googlegroups.com	
To: 	skos-dev  <mailto:skos-dev@googlegroups.com>
<skos-dev@googlegroups.com>	
References:
<mailto:d8e4f408-dc49-49e9-be28-e2c4ad9c11cf@i18g2000pro.googlegroups.com>
<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  <mailto:steve.rich...@azgs.az.gov>
<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

--~--~---------~--~----~------------~-------~--~----~

You received this message because you are subscribed to the Google Groups
"skos-dev" group.

To post to this group, send email to skos-dev@googlegroups.com

To unsubscribe from this group, send email to
skos-dev+unsubscribe@googlegroups.com

For more options, visit this group at
http://groups.google.com/group/skos-dev?hl=en

-~----------~----~----~----~------~----~------~--~---





-- 

Stephen M. Richard

Section Chief, Geoinformatics

Arizona Geological Survey

416 W. Congress St., #100

Tucson, Arizona, 85701 USA



Phone: 

Office: (520) 209-4127

Reception: (520) 770-3500 

FAX: (520) 770-3505



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 15:59:53 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:39:04 GMT