Sean barker wrote: (01)
> "I come to bury Caesar, not to praise him"
>
> The title for this thread is "interpreting OWL"; the discussion of
> EXPRESS was a thought experiment to see just how perversely one could
> interpret OWL, essentially as a way of asking, "What level of
> interoperability does one get from using OWL?" The answer has come back,
> loud and clear, "OWL doesn't help at all." This is not a discussion I'd
> observed before, but is important in setting the right (low) level of
> expectation for the Semantic Web.
> (02)
Well, on the CL exploder there has been a discussion of "Why XCL?", and
the assessment is: Not because XML is good, but because students and
managers believe it is all there is. That IMO applies also to OWL. It
is the only modeling language W3C has, and thus it will come to dominate
that part of the trade that is looking for a way up from XML Schema, and
from the same fount of knowledge. One thing is certain: no one will
ever again be taught EXPRESS. (03)
> -------------
>
> Following the comments about not being able to represent cyclic
> structures in OWL, my hacker's instincts kicked in, and remembering that
> EXPRESS data models can be translated into XML messages, which are also
> tree structured, it strikes me that one could:
>
> a) Define two integer properties Id, and Ref
> b) Create an implied relationship, that a value of Ref is a link to a
> thing with its Id the same value as Ref
> c)
> Id Ref
> 1 2
> 2 3
> 3 1
>
> While this is not a mechanism explicitly understood by OWL, it a cyclic
> structure that could be expressed in OWL.
> (04)
And as a consequence it may as well be in XML, because no tool that does
anything useful with OWL will do anything useful with these undefined
unrelated properties. If you don't use the language to define any
relationship between these primitive relations, then they don't have any
relationship, except to you. (05)
> Given lots of cunning graduates being expected to provide theses using
> OWL, one can confidently predict that where it does not do what they
> want directly, it will be twisted to do it indirectly.
> (06)
Yes. I recently coached a new Ph.D. who made an OWL metamodel of XML
Schema, developed an OWL ontology for the domain and defined his own
mapping language for the semantic associations. It is all in OWL
formally, but his tooling is the only thing that can process his mapping
primitives to do semantic mediation. But by being in OWL, it was
academically acceptable, while doing the same thing in XSLT is not. (07)
I don't want to decry OWL for its weaknesses, because as a mindset, it
is a great leap forward from UML and XML Schema. Without the climate
created by OWL and the Semantic Web, no one would have bothered making a
formal definition of fUML. I don't expect the "Semantic Web" to have
much value as a source of machine processable knowledge, but I do think
it will produce a generation of modelers and computer scientists who
actually model concepts instead of data representation. That can only
be good, no matter how much effort is wasted on hype, rose painting and
the pursuit of bandwagons. (08)
-Ed (09)
--
Edward J. Barkmeyer Email: edbark@xxxxxxxx
National Institute of Standards & Technology
Manufacturing Systems Integration Division
100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528
Gaithersburg, MD 20899-8263 FAX: +1 301-975-4694 (010)
"The opinions expressed above do not reflect consensus of NIST,
and have not been reviewed by any Government authority." (011)
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