- From: Jim Hendler <hendler@cs.umd.edu>
- Date: Mon, 9 Dec 2002 18:29:44 -0500
- To: Ian Horrocks <horrocks@cs.man.ac.uk>, Deborah McGuinness <dlm@ksl.stanford.edu>
- Cc: www-webont-wg@w3.org
At 8:09 PM +0000 12/9/02, Ian Horrocks wrote: >This has been overtaken by Jeremy's proposal and the resulting >discussion - see [1] > >Ian Ian - forgive my stupidity, but I'm not sure I see how Jeremy's email and the resulting discussion answers the question that Deb is asking. Are you claiming it breaks this thing about OWL entailments? If so, then we go back to Deb's original proposal to have hasValue in Lite, but with IFF semantics. I understand you still would oppose that, but I'm just trying to make sure I understand - is the following a correct sumary of your position? i. You oppose adding hasvalue with if in Lite, becuase it has iff in DL (c.f. your response to Jeremy) ii. You oppose havine hasvalue with iff in Lite, because you argue it pushes up the computational complexity of Lite If I've gotten this wrong, please help -- I think it important we understand this issue well, because I expect we will be voting on it this Thursday (as I see no consensus emerging) -JH > >[1] http://lists.w3.org/Archives/Public/www-webont-wg/2002Dec/0054.html > > >On December 5, Deborah McGuinness writes: >> >> > >> >> 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 >> > >> > *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" >> > * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] >> > * Other mail archives: [this mailing list] [other W3C mailing lists] >> > * Mail actions: [ respond to this message ] [ mail a new topic ] >> > >> > ------------------------------------------------------------------------ >> > >> > 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" >> > * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] >> > * Other mail archives: [this mailing list] [other W3C mailing lists] >> > * Mail actions: [ respond to this message ] [ mail a new topic ] >> >> -- >> 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 >> -- 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
Received on Monday, 9 December 2002 18:29:54 UTC