RE: Classifying with Inequalities

If OWL classifiers are moving ahead of OWL, and adding in capabilities
based on practical needs, this is a good thing.  However, it does seem
to indicate that OWL is already behind the times, and validates the
perception that OWL was designed without paying much attention
to the demands of real-world applications.  It would
be very unfortunate if users have to resort to using language constructs
in Cerebra and/or Racer that do not conform to the OWL spec, since that
encourages a proliferation of non-regulated modeling constructs, which
is exactly the kind of thing that a language standard is supposed to prevent.

Can anyone suggest if there is a possibility that OWL or SWRL could
standardize on a set of inequality properties within a reasonable time frame,
so that we don't have to each invent our own, and then do alignments down 
the road?
Are there semantic issues that need to be resolved, or are the semantics 
sufficiently
obvious that we could just informally agree on them, and then put them on a 
committee's
TO DO list?

Cheers, Bob


At 09:36 AM 5/10/2004, Gary Ng wrote:
>Hi Bob,
>
>Unfortunately classifying by datatype restrictions whereby each datatype
>may be a user-defined range is currently not in the OWL specification,
>but it is not incompatible.
>
>I believe there are two reasoners which has the capability of doing the
>classification you have described: Cerebra and Racer. Cerebra uses an
>extension of OWL to specify user defined ranges.
>
>I will leave the list to reply to the question of why OWL did not
>include such features. But IMHO it was more logistics than
>technicalities. It has something to do with the stability of RDF
>datatypes and integration issues with XMLSchema datatype at the time, to
>fully integrate such features would have been another project in itself.
>
>
>Cheers
>
>Gary
>
>Gary Ng, Ph.D.           <gary.ng@networkinference.com>
>Network Inference Inc.
>5900, Laplace Court, Suite 250
>Carlsbad, San Diego, CA 92008
>Tel: +1 (760) 476 0650
>
>
>-----Original Message-----
>From: www-rdf-logic-request@w3.org [mailto:www-rdf-logic-request@w3.org]
>On Behalf Of Bob MacGregor
>Sent: 10 May 2004 09:11
>To: www-rdf-logic@w3.org
>Subject: Classifying with Inequalities
>
>
>We do a lot of reasoning with inequalities, e.g., restricting
>events within certain dates, or logging observations
>within rectangular regions. It would be extremely
>useful to be able to define classes that include such
>restrictions and to arrange them in a classification hierarchy.
>My impression is that there
>is no inequality operator for any of the OWL variants.  My
>question is, are inequalities compatible with OWL, or is this
>yet another area (e.g., like metadata and property composition)
>where the existing OWL infrastructure falls far short of user needs?
>
>In either case, it would be very nice if there were inequality
>properties
>for greater than, less than, greater-than-or-equal, less-than-or-equal
>blessed by a W3C standard. Is there any possibility of this
>happening in the near future?
>
>Note:  Loom added the ability to classify scalar
>intervals, and restrictions that reference them, very early on.
>Thus, the notion of the kind of classification I need has been
>around for a very long time.
>
>Cheers, Bob

=====================================
Robert MacGregor
Senior Project Leader
macgregor@isi.edu
Phone: 310/448-8423, Fax:  310/822-6592
Mobile: 310/251-8488

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