- From: Ian Horrocks <horrocks@cs.man.ac.uk>
- Date: Thu, 2 May 2002 09:12:47 +0100
- To: "Jonathan Borden" <jonathan@openhealth.org>
- Cc: "Enrico Motta" <e.motta@open.ac.uk>, "Deborah McGuinness" <dlm@ksl.stanford.edu>, <www-webont-wg@w3.org>
On May 2, Jonathan Borden writes: > Ian Horrocks wrote: > > > > I would suggest that where universal quantification is being widely > > used in practice, it is either as a result of its being the only > > available option and/or the fact that many users assume an implicit > > existential - it never occurs to them that people all of whose > > children are doctors may not have any children at all (I would hardly > > bother telling you what type their children must be if they don't have > > any children, would I?). > > > > Hmm. What about combining toClass with minCardinality, so that there would > have to be, e.g., at least one child, and that child would have to be a > doctor -- or would that just be a minCardinalityQ? No. As I think Deb already pointed out, asserting (minCardinality 1 P) along with (toClass P C) means that there can never by any Ps that are not Cs. Saying (minCardinalityQ 1 P C) means that there is at least one P that is a C, but says nothing about the existence or otherwise of other Ps that are not Cs. So, (minCardinalityQ P 1 C) is equivalent to (hasClass P C). As I mentioned at one of the earlier F2F meetings, the Q restrictions are the most general and can capture both hasClass and toClass: (maxCardinalityQ 0 P (not C)) is equivalent to (toClass P C). Ian > > Jonathan
Received on Thursday, 2 May 2002 04:16:01 UTC