W3C home > Mailing lists > Public > www-webont-wg@w3.org > March 2003

Re: Proposed simplification of datatype expressions

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Thu, 13 Mar 2003 18:07:39 +0000
Message-ID: <15984.51435.804868.371464@merlin.horrocks.net>
To: Sean Bechhofer <seanb@cs.man.ac.uk>
Cc: Dan Connolly <connolly@w3.org>, <www-webont-wg@w3.org>

On March 13, Sean Bechhofer writes:
> 
> On Thu, 13 Mar 2003, Dan Connolly wrote:
> 
> >
> > On Thu, 2003-03-13 at 10:47, Ian Horrocks wrote:
> > > I know this is rather last-minute, but I would like to propose a
> > > couple of small simplifications to the language that would
> > > significantly improve ease of implementation of datatype reasoning in
> > > both DL and Lite.
> > >
> > > 1. Change the specification of cardinality constraints so that they
> > > can only be applied to individual valued properties and not to data
> > > valued properties. This seems to be a relatively small loss as most
> > > data valued properties turn out to be functional, and it is hard to
> > > think of realistic examples where local/arbitrary-valued cardinality
> > > constraints are required.
> >
> > I can support going to 0/1/many. But constraining a property
> > to be functional is a cardinality constraint, no?
> > I don't think I'm quite clear on what you're after.
> 
> I think that what Ian is suggesting that you're still allowed to assert
> whether a data valued property is functional or not, but that arbitrary
> cardinality constraints involving data valued properties can't be used in
> descriptions. So, for example, we can still say that age is functional,
> and thus everyone can only have at most one age, but we can't form a
> description of:
> 
> "people who have at least three values for property x."
> 
> where x is a data valued property. 

This is exactly what I had in mind.

Ian

> I, too, struggle to think of an example
> where one would actually want to use such a construct (but am open to
> suggestion)....
> 
> 	Sean
> 
> -- 
> Sean Bechhofer
> seanb@cs.man.ac.uk
> http://www.cs.man.ac.uk/~seanb
> 
Received on Thursday, 13 March 2003 12:06:57 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:57:58 GMT