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RE: OWL clarifications

From: Smith, Michael K <michael.smith@eds.com>
Date: Tue, 3 Dec 2002 10:49:18 -0600
Message-ID: <B8E84F4D9F65D411803500508BE322141241A867@USPLM207>
To: Aseem Das <aseem.das@blackpearl.com>, public-webont-comments@w3.org


> 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:

"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 Tuesday, 3 December 2002 11:49:36 GMT

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