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Re: Case for Reinstatement of Qualified Cardinality Restrictions

From: Sean Bechhofer <seanb@cs.man.ac.uk>
Date: Tue, 22 Apr 2003 17:20:07 +0100 (GMT Daylight Time)
To: Jeff Heflin <heflin@cse.lehigh.edu>
cc: Jim Hendler <hendler@cs.umd.edu>, Jonathan Borden <jonathan@openhealth.org>, webont <www-webont-wg@w3.org>
Message-ID: <Pine.WNT.4.44.0304221707360.2340-100000@potato>

On Tue, 22 Apr 2003, Jeff Heflin wrote:
> I have serious concerns about reopening this issue. The chief reason it
> was omitted is that hardly any DAML users understood it and few (if any)
> attempted to use it. I'd like to see compelling evidence that things
> would be different if we added the feature back to OWL. I do not find
> Rector's comments compelling because
> 1) It would be more compelling if the need for a particular DL feature
> came from somebody who wasn't in the DL community. It's not suprising he
> finds it important b/c he's been using it in his DL work. I find that
> some of Deborah's comments present a counter-point Rector's. She said
> the medical community that uses Protege has never requested this sort of
> feature. Furthermore, although she is experienced with DLs, believes
> QCR's can be confusing to novices.

I don't think this is necessarily the case. Although Alan has been working
with DLs, I wouldn't particularly place him as being "in the DL
community". In fact, QCRs were not part of the language (GRAIL) that a lot
of his original work was done in. Once QCRs were included in D+O, they
ended up being used *precisely* because they were what was required.

> 3) I think the factor that makes QCRs most confusing in OWL is the
> difficulty in expressing them cleanly in triples. Currently, the
> Restriction class is a place to hang each restriction that is applicable
> to a property. Currently, each of these is a binary predicate so the
> following is perfectly fine.

Surely this simply highlights the difficulty of representing a rich
language in triples rather than providing a case for the non-inclusion of
QCRs in the language. I'd claim that representing *any* OWL ontology as
triples introduces complications, but then I'm sure you're already aware
of my opinion on that... :-)

As with Ian, I should make it clear that although I share an affiliation
with Alan, these are independent opinions.....

In case it's not already obvious, I'm in favour.


Sean Bechhofer
Received on Tuesday, 22 April 2003 12:22:43 UTC

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