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RE: OWL clarifications

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Wed, 4 Dec 2002 14:25:33 +0000
Message-ID: <15854.4189.626383.745946@galahad.cs.man.ac.uk>
To: "Smith, Michael K" <michael.smith@eds.com>
Cc: Aseem Das <aseem.das@blackpearl.com>, public-webont-comments@w3.org

On December 3, Smith, Michael K writes:
> 
> 
> > 1.  Are local property restrictions not part of OWL Lite? (somewhere the
> > doc. says OWL DL next to anonymous classes)  Having local property
> > restrictions specified as anonymous classes, makes it difficult to present
> > this information to an end buisness user in a clear and meaningful way.
> Why
> > are  local property restrictions specified as anonymous classes instead of
> > say just specifying the restrictions on the class directly?
> 
> You've got property restrictions in OWL Lite, but only using named classes.
> 
> Anonymous classes are not permitted in OWL Lite restrictions.
> 
> See the following section from the Feature Synopsis.
> (http://www.w3.org/TR/2002/WD-owl-features-20020729/)
> 
>  ... OWL Lite has a subset of the full OWL language constructors and
>  has a few limitations. Unlike the full OWL language (and DAML+OIL),
>  classes can only be defined in terms of named superclasses and only
>  certain kinds of restrictions can be used. Equivalence for classes,
>  and subclass between classes are all only allowed on named
>  classes. Similarly, property restrictions in OWL-Lite use named
>  classes. 
> 
> > 2.  Is "rdf:type" the correct and only way for specifying classes as
> > instances of other classes?
> 
> Yes, rdf:type is how you specify classes as instances.  I think that
> in OWL Full the following would be ok also.
> 
> <owl:Class rdf:id="A" />
> <owl:Class rdf:id="B" />
> <A rdf:about="#B" />
> 
> > 3. Can minCard, maxCard and cardinality restrictions be applied to global
> > property definitions or are only allowed for local property restrictions?
> 
> They are local.  From the OWL Reference:

It might be worth mentioning that they can be given global effect
simply by asserting "Thing" to be a subClassOf the relevant
restriction.

Ian

> 
> "OWL cardinality restrictions are referred to as local restrictions
>  since they are stated on properties with respect to a particular
>  class."
> 
> > 4.  Are local property restrictions on a class, inherited to its
> subclasses?
> 
> Yes.
> 
> > 5. We have a requirement for representing user-defined facets.  How can
> > these be specified in OWL?
> 
> Can you give me an example of what you are looking for?
> 
> > Thankyou in advance for your replies
> > Aseem Das
> > Black Pearl Inc.
> 
> Hope this helps.
> 
> - Mike
> 
> Michael K. Smith, Ph.D., P.E.
> EDS - Austin Innovation Centre
> 98 San Jacinto, #500
> Austin, TX  78701
> 
> * phone: +01-512-404-6683
> * mailto:michael.smith@eds.com
> 
> 
> -----Original Message-----
> From: Aseem Das [mailto:aseem.das@blackpearl.com]
> Sent: Monday, December 02, 2002 6:49 PM
> To: public-webont-comments@w3.org
> Subject: OWL clarifications
> 
> 
> 
> 
> 
> We are trying to build an ontology building/editing environment for business
> end users, using OWL as the underlying representation language and it would
> be helpful to get some clarifications about the language.
> 
> 1.  Are local property restrictions not part of OWL Lite? (somewhere the
> doc. says OWL DL next to anonymous classes)  Having local property
> restrictions specified as anonymous classes, makes it difficult to present
> this information to an end buisness user in a clear and meaningful way.  Why
> are  local property restrictions specified as anonymous classes instead of
> say just specifying the restrictions on the class directly?
> 
> 2.  Is "rdf:type" the correct and only way for specifying classes as
> instances of other classes?
> 
> 3. Can minCard, maxCard and cardinality restrictions be applied to global
> property definitions or are only allowed for local property restrictions?
> 
> 4.  Are local property restrictions on a class, inherited to its subclasses?
> 
> 5. We have a requirement for representing user-defined facets.  How can
> these be specified in OWL?
> 
> Thankyou in advance for your replies
> Aseem Das
> Black Pearl Inc.
> 
> 
Received on Wednesday, 4 December 2002 09:19:14 GMT

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