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RE: WOWG: Response to HP -- some changes (Guide, Overview, Ref) we may need to make

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 12 Jun 2003 13:57:14 +0200
To: "Jim Hendler" <hendler@cs.umd.edu>, "webont" <www-webont-wg@w3.org>
Message-ID: <BHEGLCKMOHGLGNOKPGHDIELDCBAA.jjc@hpl.hp.com>


In any final response, it is worth pointing out that we deleted the complete
OWL DL consistency checker from test cases (even though that was not in last
call).

Jeremy

> -----Original Message-----
> From: www-webont-wg-request@w3.org
> [mailto:www-webont-wg-request@w3.org]On Behalf Of Jim Hendler
> Sent: 09 June 2003 18:10
> To: webont
> Subject: WOWG: Response to HP -- some changes (Guide, Overview, Ref) we
> may need to make
>
>
>
> In working on my new version of my response to Martin Merry, I tried
> to answer his concern that:
>
> so we believe that if the documents made clearer that using BOTH
> oneOf and inverseOf (and their various forms) could lead to an
> unexpected rise in complexity, we would set the expectation
> correctly. In that way the current OWL DL subset would be easier to
> understand, and the design rationale behind it better understood.
>
> Thus, given these two below, we propose that the WebOntology working
> group will make the issue above clearer and will write text to appear
> in the Reference, S&AS and Test documents that explain the above.
>
> by quoting from Ref, Guide and Overview.  However, what I found in
> those three is that as we've currently written it, Ref captures the
> real situation better than the other two -- but we recommend people
> read the other two first.  In addition, the way that Guide and
> Overview describe DL v. Lite could be fixed to better handle the
> above. Also, S&AS, which should have a "definitive" statement on this
> doesn't.  This would help a lot to add
>
> Here are my suggestions for all of these -- Editors, please let me
> know if you accept these changes (or similar ones of your own
> chosing), if not, we will need to schedule telecon time to discuss.
>   thanks
>   JH
>
>
> ---FIXING GUIDE ----
>
> Specifically, Guide reads (Section 1.1)
>
> OWL DL supports those users who want the maximum expressiveness
> without losing computational completeness (all entailments are
> guaranteed to be computed) and decidability (all computations will
> finish in finite time) of reasoning systems. ... OWL DL was designed
> to support the existing Description Logic business segment and has
> desirable computational properties for reasoning systems.
>
> which is true, but that last sentence does seem to imply efficiency
> rather than decidability (since the first sentence mentions
> decidability).
>
> but OWL Lite reads:
>
> OWL Lite supports those users primarily needing a classification
> hierarchy and simple constraint features. ... . It should be simpler
> to provide tool support for OWL Lite than its more expressive
> relatives, and provide a quick migration path for thesauri and other
> taxonomies.
>
> but doesn't mention complexity.
>
> I suggest that we delete the last line of the DL description, and add
> the following line (from the Reference) to the Lite Description:
>
> (Reference section 8.3)
> The limitations on OWL Lite place it in a lower complexity class than
> OWL DL. This can have a positive impact on the efficiency of complete
> reasoners for OWL Lite.
>
> This would help set appropriate expectations qua the issues
> brought up by Merry
>
>
> ----- Fixing Overview --------
>
> Overview reads:
>
> (section 1.3)
> OWL Lite supports those users primarily needing a classification
> hierarchy and simple constraints. For example, while it supports
> cardinality constraints, it only permits cardinality values of 0 or
> 1. It should be simpler to provide tool support for OWL Lite than its
> more expressive relatives, and OWL Lite provides a quick migration
> path for thesauri and other taxonomies.
>
> I would add a sentence that reads:  "Owl Lite also has a lower formal
> complexity than OWL DL, see <reference section 8.3> for further
> details."
>
> This would also help in addressing Merry's issues.
>
> -------- Fixing S&AS -------
>
> S&AS, since it is targeted to the expert, would be an obvious place
> to include some technical details of the distinction between Lite and
> DL from a complexity point of view.  I believe the introduction could
> easily add a paragraph stating that OWL FUll is undecidable, OWL DL
> is decidable but in complexity class NexpSpace (or whatever), and OWL
> Lite is decidable and in complexity class ExpSpace.
>
> It might even be worth saying that the combination of inverses and
> individuals (oneOf, hasValue) lead to the extra complexity for OWL DL.
>
>
> ======================
> --
> 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 Thursday, 12 June 2003 07:57:12 GMT

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