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Re: Case for Reinstatement of Qualified Cardinality Restrictions [proposed reply]

From: Dan Connolly <connolly@w3.org>
Date: 11 Jun 2003 10:36:41 -0500
To: www-webont-wg@w3.org
Message-Id: <1055345801.23337.27.camel@dirk.dm93.org>

Hmm... it seems when we made the 8 May decision on QCRs, nobody
got back to the commentor.

I updated the issues list and I propose to get back to him thusly...

Jim/Guus, OK by you? Anybody find any reason not to send this?


On Wed, 2003-04-16 at 03:43, Alan Rector wrote:
[...]
> I therefore wish to propose  that  qualified cardinality restrictions be re-instated, possibly using an amended syntax for clarity.
> 
> Below I discuss in turn each of the original points cited in opposing qualified cardinality restrictions as quoted in the Issues document and then give a set of eight use cases/examples.  Further examples can be made available if needed.
[...]

Thanks for your thorough discussion and proposal. It compellingly
argues against the justification for our earlier design decision.
The issue was re-opened and he working group considered a number
of options; we decided, 8 May,

        ... to POSTPONE this issue for the following reasons: 
              * OWL already contains one QCR construct:
                owl:someValuesFrom (QCR with minimal cardinality of 1)
                which covers some frequent-occurring cases of QCRs.
              * There are some workarounds for QCRs, using the
                rdfs:subPropertyOf construct. These can be used in
                simple cases, such as the example in the Guide below.
                The WG agrees that these workarounds are more
                problematic for complex part-of relations such as
                pointed out by Alan Rector in his use cases a) and b).
              * The evidence on whether users need this is mixed.
                Rector's use cases are compelling, but Protege (which
                has a large user community) has not reported user
                requests for this feature.
              * Inclusion of this feature will put additional burden on
                implementations. For example, it is nontrivial to add
                this to Protege.
        
        
        The Working Group therefore POSTPONES the full treatment of
        QCRs, while considering possibilities for making idioms or other
        guidelines for QCRs available to the community.

  --
http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I3.2-Qualified-Restrictions

Please let us know if this decision to (a) acknowledge
that our design is lacking, but (b) postpone further design
work to a future version is acceptable.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 11 June 2003 11:36:24 GMT

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