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Re: [SKOS] OWL DL compatibility

From: Dan Brickley <danbri@danbri.org>
Date: Wed, 21 Feb 2007 12:05:14 +0100
Message-ID: <45DC276A.4090201@danbri.org>
To: Mark van Assem <mark@cs.vu.nl>
Cc: Antoine Isaac <aisaac@few.vu.nl>, Alistair Miles <a.j.miles@rl.ac.uk>, SWD WG <public-swd-wg@w3.org>, SKOS <public-esw-thes@w3.org>

Mark van Assem wrote:
> Hi Antoine, Dan,
> 
>> - the need for annotating owl:Class is not obvious for me (typical 
>> thesauri in Cultural Heritage do not pretend to be ontologies). Perhaps 
> 
> I think Alistair's idea was to enable usage of SKOS properties to 
> describe OWL classes in proper ontologies.
> 
> There is a problem in OWL DL with recording different kinds of labels 
> (e.g. which to use for display or not, which is the vernacular label, 
> etc.) because rdfs:label is an AnnotationProperty, which cannot be 
> specialized with rdfs:subPropertyOf. However, this would be the 
> preferred way to maintain semantic interoperability (you can always dumb 
> down to rdfs:label).
> 
> SKOS might fill this gap, but it can only do so if SKOS proeprties are 
> not restricted to skos:Concept and are NOT AnnotationProperties (else 
> they could not be specialized themselves as might be expected). But if 
> they are to be applied to _classes_ in DL, they MUST be 
> AnnotationProperties...
> 
> Dilemma, dilemma...

How about restricting the SKOS stuff to just work with SKOS stuff, not 
with OWL. But then defining a bridge property that links from a class to 
a (possibly anonymous) SKOS entity that "shadows" it for purposes of 
documentation.

ie.

not:
<owl:Class>
  <skos:prefLabel>Foo</etc

...but

<owl:Class>
  <skos:bridge>
   <skos:Concept>
    <skos:prefLabel>Foo</etc

Question: do the DL puritans allow things like this? Presumably "bridge" 
would be an AnnotationProperty.

Let me see. http://www.w3.org/TR/owl-ref/#Header

So...

skos:bridge rdf:type owl:AnnotationProperty .

"The object of an annotation property must be either a data literal, a 
URI reference, or an individual."

We can't define a formal range on skos:bridge, but informally we can 
spread an expectation that it be used to point to individuals that are 
SKOS Concepts.

Note that we needed even write that type information in the RDF graph, 
and that the much-maligned RDF/XML syntax allows a notation for this:

<owl:Class rdf:ID="Car">
  <skos:bridge skos:prefLabel="Car" skos:altLabel="BrmBrm"/>
</owl:Class>

Note also that this idiom gets into the very interesting territory of 
idioms for relating ontological and skos models. However, here, I am 
suggesting it purely as a documentation convention. Whether a common 
design could serve both purposes, I have no idea right now. In some ways 
it would be nice, but we would have to define domain, range and inverses 
solely in prose. BTW one of the property names Alistair and I were 
throwing around for this was "skos:as" (inverse: skos:it). This would 
link between inviduals ("dan") and classes ("Person") and corresponding 
topics in a SKOS scheme:

How might that look here?

Assuming:
    skos:as rdf:type owl:AnnotationProperty .

<owl:Class rdf:ID="Person">
  <skos:as skos:prefLabel="Person" skos:altLabel="Guy"/>
</owl:Class>


Am I making any sense here?

cheers,

Dan

--
http://danbri.org/
Received on Wednesday, 21 February 2007 11:05:38 GMT

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