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Re: Issue: Add hasValue to OWL Lite

From: Deborah McGuinness <dlm@ksl.Stanford.EDU>
Date: Thu, 05 Dec 2002 10:44:20 -0800
Message-ID: <3DEF9E84.39DF9655@ksl.stanford.edu>
To: www-webont-wg@w3.org

>

In preparation for next week's discussion of hasValue, in going through the mailing list, this is the only
written compromise solution.  My reading of this is a proposal that says:

MexicanRestaurant = (hasValue foodServing MexicanFood)

then if x is known to be an instance of mexicanRestaurant then we know that x has a value of MexicanFood
for its foodServing slot

(i.e., inheritance works because hasValue is a necessary condition)

BUT
if y is known to have MexicanFood for a value of its foodServing slot then we can NOT infer that y is an
instance of MexicanRestaurant.
(i.e., recognition does not work because hasValue is not considered to be a sufficiency condition).

this proposal means that hasValue has a different semantics than it has in DAML+OIL and we would need to
decide what the semantics would be in OWL DL and OWL Full.

I was not on a telecon where I believe this issue may have been discussed more completely and if someone
who was on that call can relay any consensus, that would be useful in preparation for next week's
discussion of this issue.


> Re: Issue: Add hasValue to OWL Lite
>
> From: Jim Hendler (hendler@cs.umd.edu)
> Date: Thu, Oct 31 2002
>
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>
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>   ------------------------------------------------------------------------
>
> Message-Id: <p05111710b9e759013172@[10.0.0.16]>
> Date: Thu, 31 Oct 2002 17:05:21 -0500
> To: Ian Horrocks <horrocks@cs.man.ac.uk>, Dan Connolly <connolly@w3.org>
> From: Jim Hendler <hendler@cs.umd.edu>
> Cc: Deborah McGuinness <dlm@ksl.stanford.edu>, webont <www-webont-wg@w3.org>
> Subject: Re: Issue:  Add hasValue to OWL Lite
>
> At 3:45 PM +0000 10/31/02, Ian Horrocks wrote:
> >On October 29, Dan Connolly writes:
> >>
> >>  On Tue, 2002-10-29 at 18:34, Ian Horrocks wrote:
> >>  >
> >>  > The problem with adding hasValue to OWL Lite is that it wouldn't be
> >>  > Lite any more. The lack of hasValue in Lite is, from an implementation
> >>  > point of view, the main thing that differentiates it from fast -
> >>  > hasValue is very tough to deal with, and is responsible for pushing
> >>  > the worst case complexity of reasoning in fast OWL from ExpTime to
> >>  > NExpTime.
> >>
> >>  Could you unpack that a bit?
> >>
> >>  Could you give an example, maybe?
> >
> >I'm not sure. This isn't anything to do with reasoning techniques or
> >specific examples, it is a fundamental property of the logic that
> >basic inference problems (satisfiability, subsumption, entailment) are
> >much harder when we add extensionally defined classes (which is what
> >hasValue amounts to).
> >
> >If you want an intuition, it comes down to the loss of the tree(ish)
> >model property. Without this property, it is very hard to devise
> >decision procedures that work in a goal-directed way and that know
> >when they are done.
> >
> >Ian
>
> Ian - the question arose at the Telecon as to whether this was true
> for both the IF and the ONLY IF (i.e. hasValue -> X vs X -> hasValue)
> -- that is, does saying "All Mexican restaurants serve Mexican food"
> cause the problem if you're not expected to be able to say "all
> places that serve Mexican food are Mexican restaurants"??
>   -JH
>
> --
> Professor James Hendler                           hendler@cs.umd.edu
> Director, Semantic Web and Agent Technologies     301-405-2696
> Maryland Information and Network Dynamics Lab.    301-405-6707 (Fax)
> Univ of Maryland, College Park, MD 20742          240-731-3822 (Cell)
> http://www.cs.umd.edu/users/hendler
>
>   ------------------------------------------------------------------------
>
>    * Next message: Peter F. Patel-Schneider: "Re: Guide: draft of Oct 31 (goofy TranstiveProperty use)"
>    * Previous message: Smith, Michael K: "RE: Guide: draft of Oct 31"
>    * In reply to: Ian Horrocks: "Re: Issue: Add hasValue to OWL Lite"
>    * Next in thread: Jos De_Roo: "Re: Issue: Add hasValue to OWL Lite"
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--
 Deborah L. McGuinness
 Knowledge Systems Laboratory
 Gates Computer Science Building, 2A Room 241
 Stanford University, Stanford, CA 94305-9020
 email: dlm@ksl.stanford.edu
 URL: http://ksl.stanford.edu/people/dlm
 (voice) 650 723 9770    (stanford fax) 650 725 5850   (computer fax)  801 705 0941
Received on Thursday, 5 December 2002 13:45:10 GMT

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