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Re: Issue 5.17 XML presentation syntax for OWL

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 19 Dec 2002 09:01:30 -0500 (EST)
Message-Id: <20021219.090130.93334808.pfps@research.bell-labs.com>
To: heflin@cse.lehigh.edu
Cc: www-webont-wg@w3.org

From: Jeff Heflin <heflin@cse.lehigh.edu>
Subject: Re: Issue 5.17 XML presentation syntax for OWL
Date: Mon, 16 Dec 2002 15:37:15 -0500

> Peter,
> 
> I've finally had a chance to look at your XML presentation syntax in
> detail. In general, it looks very good. However, I have a few
> suggestions:
> 
> 1) I agree with Masahiro that it is odd to have SubClassOf as a child of
> Ontology, especially since there is an alternative way to represent the
> same information. 

I am not aware of an alternative way.  Remember that SubClassOf allows
descriptions on both sides.

> 2) I think the implicit intersectionOf that is used for multiple
> descriptions is bound to lead to confusion. Perhaps this could be fixed
> by limiting a Class to at most one description? This will force people
> to explicitly use the intersectionOf or unionOf as appropriate.

> 3) Is EnumeratedClass necessary? Doesn't a Class with a OneOf do the
> same thing?

> 4) Why have SubPropertyOf as a subelement of Ontology? You have a super
> attribute in ObjectProperty and DataProperty that does the same thing.

The XML syntax is designed to stick as close to a frame syntax as possible,
and not to be tied to the triple syntax.  It is also not designed to be as
sparse as possible.  Both of these characteristics have been deemed to be
desirable, and would be compromised by the above changes.

> 5) Can we change DatatypeProperty and ObjectProperty to Property, with
> an attribute to distinguish between the two? We could make Object the
> default value for this attribute.

In my opinion, default syntax values are not a good idea.

> 6) Can we change the EquivalentClasses, EquivalentProperties, and
> SameIndividual elements (which are are currently subelements of
> ontology) to subelements of Class, Property, and Individual,
> respectively?

See above.

> 7) Do we really need to distinguish between DataRestrictions and
> IndividualRestrictions? Let's just call them Restrictions.

There are implementation reasons for doing this.

> 8) The use of cardinality attributes with Restrictions that have
> subelements is confusing. It could be mistakenly interpreted to mean the
> same thing as the use of cardinalityQ in DAML+OIL. Perhaps it would be
> clearer to change the cardinality attributes to elements.

Possible.

> 9) How about changing all element and attribute names to start with
> lower case characters? The OWL exchange syntax capitalization looks
> funny here.

Possible.

> 10) Finally, I do not think Ontology is a suitable top-level element for
> documents that contain only instances. This is the same discussion that
> we got into a few weeks ago, and as I understand it, the guide is going
> to have specific terminology for distinguishing between "ontology"
> documents and other documents. It will be very confusing for users of
> the XML presentation syntax if the term ontology is used differently
> than it is in the guide. I suggest we have owl as our root element, with
> an ontology child and perhaps a data child.

Well, Ontology is already used elsewhere in roughly the same circumstances,
so your proposal should be directed first there.

> Thanks again. If you like, I'd be happy to help get the XML presentation
> syntax into suitable format for the appendix.
> 
> Jeff


peter
Received on Thursday, 19 December 2002 09:01:39 GMT

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