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Re: LANG: owl:ontology

From: Jeff Heflin <heflin@cse.lehigh.edu>
Date: Mon, 16 Sep 2002 10:52:45 -0400
Message-ID: <3D85F03D.959A9E3D@cse.lehigh.edu>
To: Jim Hendler <hendler@cs.umd.edu>
CC: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, www-webont-wg@w3.org

I believe the issue of importing parts of ontologies is a separate issue
from from 5.6. I think that it is much more complicated and am currently
opposed to including it in this version of the language. As such, I'd
like to see it raised and addressed as a separate issue. At such time as
it is opened, I'll discuss my reasons for being opposed to it.


Jim Hendler wrote:
> I was going to wait for others to weigh in before deciding to
> continue this, but I realized that there is some ambiguity and that
> perhaps Peter and I are making different assumptions:
> >
> >Peter wrote:  [snip
> >In the current systems (DAML+OIL) ontologies are documents, at least as far
> >as I can see.  Having ontologies be documents is a viable solution in my
> >eyes, and provides an elegant solution to which information to import.
> >[snip]
> >
> >The DAML+OIL documents are rather vague.  However, an imports refers to a
> >URI and it seems to me that this means to import the contents of the
> >document, as there is no other potential thing to import.
> He is right that the document is vague - what it says is:
>  From the DAML+OIL TR [1]
> >Each daml:imports statement references another DAML+OIL ontology
> >containing definitions that apply to the current DAML+OIL resource.
> >Each reference consists of a URI specifying from where the ontology
> >is to be imported from. See the example above. Imports statements
> >are transitive, that is, if ontology A imports B, and B imports C,
> >then A imports both B and C. Importing an ontology into itself is
> >considered a null action, so if ontology A imports B and B imports
> >A, then they are considered to be equivalent.
> I have been assuming that when I define a daml:ontology (which gets
> its own URI) then an import statement points at that definition, not
> at the document which it appears in.   Thus, when Peter says "this
> means to import the contents of the document" I don't think I agree.
> I think it means to import those statements that appear associated
> with the ontology URI (not the document URL) and that it may be an
> unwarranted assumption to assume that all the triples of any type
> appearing in the rdf:RDF of that document are necessarily assumed to
> be part of the ontology.
> Jeff's use of the daml:imports as magic syntax [2] primarily focused
> on people wanting to import everything, but some of the mail on the
> original thread (see [3] and the many threads around it that it
> spawned and/or spawned it) pointed out the desire to only include
> some properties without importing the whole ontology (using cyc as an
> example). For an example of someone using stuff from other ontologies
> without importing see [4] and there's lots of other examples out in
> the real web (this is one of my students, so I got to see it, and
> then went seaching and found many more - in fact, I can find very few
> ontologies defined since the original Darpa set that use
> "daml:imports")
> I'm looking for a solution that makes it clearer what is imported,
> and allows some control over that.
>   -JH
> p.s. I have answers to Peter's challenge of what gets included given
> my scheme, but I'll wait until I see whether other people care about
> this issue before sending yet another long note...
> [1] http://www.w3.org/TR/daml+oil-reference#imports-def
> [2]
> http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.6-daml:imports-as-magic-syntax
> [3] http://lists.w3.org/Archives/Public/www-rdf-logic/2002Apr/0060.html
> [4] http://glue.umd.edu/~aloomis/498x/hw1-ont.n3
> --
> Professor James Hendler                           hendler@cs.umd.edu
> Director, Semantic Web and Agent Technologies     301-405-2696
> Maryland Information and Network Dynamics Lab.    301-405-6707 (Fax)
> Univ of Maryland, College Park, MD 20742          240-731-3822 (Cell)
> http://www.cs.umd.edu/users/hendler
Received on Monday, 16 September 2002 10:52:48 UTC

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