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Re: DAML-S expressiveness challenge #1

From: pat hayes <phayes@ai.uwf.edu>
Date: Tue, 19 Jun 2001 12:43:33 -0500
Message-Id: <v04210107b7553e838c97@[]>
To: David Martin <martin@AI.SRI.COM>
Cc: Ian Horrocks <horrocks@cs.man.ac.uk>, Dan Connolly <connolly@w3.org>, www-rdf-logic@w3.org
>Ian Horrocks wrote:
> > On June 14, David Martin writes:
> > >          DAML-S expressiveness challenge #1 -
> > >
> > > Is it possible (or is it likely to be possible in some future release of
> > > DAML+OIL or DAML-L) to express the following constraint/restriction:
> > >
> > >    "The value of an instance of property P1, in some particular
> > > context/scope/situation, must be the same as the value of an instance
> > > of property P2 in that same context/scope/situation."
> > >
> > > What do I mean by context/scope/situation?  Well, that's up for
> > > discussion, but to get us started, let's just say I mean "namespace".
> > >
> > > I know about sameIndividualAs, but a straightforward use of
> > > sameIndividualAs does not meet my requirements.  The instances of P1 and
> > > P2 don't necessarily exist yet (that is, haven't been declared
> > > anywhere); so I can't refer to them.  What I want to say is (re-phrasing
> > > the above):
> > >
> > > "when an instance of property P1 is declared, in the same namespace as
> > > an instance of property P2, they must have the same value"
> > >
> > > Can anyone suggest a way to express this, or a start toward doing so?
> >
> > You can do this now, or something close. Simply introduce a new
> > property called say "P1_or_P2" such that both P1 and P2 are asserted
> > to be subProperties of P1_or_P2. Now you can use a cardinality
> > restriction to assert that a class C has at most one P1_or_P2. Thus if
> > some instance of the class is related to individual x by P1 and
> > individual y by P2, then x=y.
>Thanks, Ian, for an interesting suggestion.  This approach is logically sound,
>I'd say, but I still have a general concern about the issue of scope.   Your
>suggestion (and other similar ones we've been kicking around) doesn't address
>the phrase of my requirement that says "in the same namespace as".  So if I
>adopt your approach, the cardinality restriction will say that class C has at
>most one P1_or_P2 ANYWHERE  on the Web, right?
>Are there any means (current or proposed) by which I could explicitly say
>class C has at most one P1_or_P2 WITHIN ANY PARTICULAR NAMESPACE?

Well, if you can conceptualize the namespace as a class NSP, then you 
can use Ian's suggestion, but applied to (P1_or_P2)_and_NSP where you 
use intersection to limit the cardinality restriction to the relevant 
part of the universe. So it remains how to define NSP, which I 
confess I do not know how to do. Maybe you could restrict on a 
property of having a certain name??

Pat Hayes

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Received on Tuesday, 19 June 2001 13:43:38 GMT

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