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Re: ShEx relation to SPIN/OWL

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Fri, 01 Aug 2014 12:56:19 -0700
Message-ID: <53DBF0E3.1000206@gmail.com>
To: Arthur Ryman <ryman@ca.ibm.com>, public-rdf-shapes@w3.org
On 08/01/2014 04:59 AM, Arthur Ryman wrote:
>
 > Peter,
 >
 > You wrote:
 > "So stating that if you use RDFS and OWL you end up with a lot of baggage
 > and lose on reusability is completely false."
 >
 > I completely agree. The above assertion is false. However, that is what
 > you wrote, not what I wrote.
 >
 > I wrote:
 > "So if you use RDFS and OWL, and include a lot of constraints, then the
 > terms are not very reusable because they carry a lot of baggage in the
 > form of inferences which may not make sense in your application."
 >
 > Note that I am describing the state of the practice. Many ontologies in
 > fact do contain a lot of inferences and this makes them less reusable.
 > This is true even in absence of constraints since W3C OWL doesn't
 > officially handle constraints, just inference rules.

It may be that there are many ontologies that support a lot of inferences.
However, there are lots of ontologies that are small and do not support a
lot of inferences.  RDFS and OWL can be used both ways.

Further, why should an ontology that supports many inferences be
undesirable, even if it is less reusable?  I don't think that you can argue
that reusability is a good in and of itself.  For example, the ontology
containing only the axiom stating that owl:Thing is a subclass of owl:Thing
is maximally reusable, but not very useful.

 > The point I was trying to make is that applications often need to impose
 > additional constraints on terms and that these constraints often depend on
 > the context.

Sure, but there is nothing in RDF or OWL that prevents working in this way.

 > Let's refocus the discussion on how an application designer would reuse an
 > externally published OWL ontology and impose additional constraints. Let's
 > assume OWL IC semantics. What would the application designer provide to
 > describe a REST API that required exactly one dcterms:title triple in the
 > request body on POST?

I fail to see how this is at all germane to RDF validation.  Why should any
consumer of RDF documents care that there is exactly one such triple?  This
constraint could be satisfied by the following RDF graph
   dcterms:title dcterms:title dcterms:title .
which doesn't seem to be of use to anyone.

If your question is how one does specify the three components of facts,
ontology, and constraints, then there are many suitable answers.  One answer
would be for the facts document have an imports directive pointing at the
ontology document and the application augment this with a separate
constraint document.  I don't see any particular problem here at all.

 > Regards,
 >
 > Arthur Ryman, PhD

peter
Received on Friday, 1 August 2014 19:56:49 UTC

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