RE: [semanticweb] RE: Sorry for misunderstanding my problem

I might have been unclear: I was referring to "property instances" (i.e.
actual usages of the object property), and I this is how I read how Gong's
question.
 
You refer to the *definition* of Object Properties. Of course, when you
*define* an object property, you can establish a link between two classes by
the *inferring* domain and range constructs in OWL. However, since the
inferring domain and range modelling in OWL is non-intuitive, I tend to not
use it at all (*). 
 
Best wishes

Martin 

(*) With "inferring domain and range modelling" I mean the fact that domain
and range are used to infer class membership, instead of  constraining the
domain and range. See de Bruijn, J., Lara, R., Polleres, A., & Fensel, D.
(2005, May 10-14). OWL DL vs. OWL Flight: Conceptual Modeling and Reasoning
for the Semantic Web. Paper presented at the 14th International World Wide
Web Conference (WWW2005), Chiba, Japan.


---------------------------
martin.hepp@deri.org, phone: +43 512 507 6465
 <http://www.heppnetz.de/> http://www.heppnetz.de /  <http://www.deri.org/>
http://www.deri.org




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From: semanticweb@yahoogroups.com [mailto:semanticweb@yahoogroups.com] On
Behalf Of John Avery
Sent: Donnerstag, 13. Oktober 2005 00:11
To: martin.hepp@deri.org; gcheng@seu.edu.cn; semantic-web@w3c.org
Cc: semanticweb@yahoogroups.com
Subject: Re: [semanticweb] RE: Sorry for misunderstanding my problem


This is not very clear, an ObjectProperty expresses a relationship
between classes or sets of classes (through the domain and range), for
an instance the property is assigned a value which (for the ontology to
be OWL DL) must be another instance (and not a class used as an instance
which would make the ontology OWL Full).

The properties still capture domain knowledge and are used between
classes. For example an ObjectProperty might say that People are related
to other People by the parent relationship.

Regards,

John Avery
School of ITMS
Univeristy of Ballarat

>>> "Martin Hepp (DERI extern)" <martin.hepp@deri.org> 10/13/05 4:16 AM
>>>
Dear Gong:

Object Properties in OWL Lite and DL can, to my knowledge, only be used
between instances, not between classes. This is why you usually do not
find
them as a means to express relationships between classes (since most
ontology creators do not want their ontology to become OWL Full, for
lack of
reasoner support). Only Annotation Properties in OWL are not limited in
this
way, but they have no formal semantics.

You can find a bit more background information in [1].

So the lack of such relationships is mainly caused by characteristics of
OWL
as an ontology language. Other ontology languages, like WSML, do not
have
this limitation.

Martin

[1] M. Hepp: "Representing the Hierarchy of Industrial Taxonomies in
OWL:
The gen/tax Approach",
Proceedings of the ISWC Workshop Semantic Web Case Studies and Best
Practices for eBusiness (SWCASE05), November 7, Galway, Irland
(forthcoming).
Available at 
 <http://www.heppnetz.de/files/SWCASE05-gentax-short-camera-ready-new.pdf>
http://www.heppnetz.de/files/SWCASE05-gentax-short-camera-ready-new.pdf


---------------------------
martin.hepp@deri.org, phone: +43 512 507 6465
 <http://www.heppnetz.de> http://www.heppnetz.de /  <http://www.deri.org>
http://www.deri.org

-----Original Message-----
From: semantic-web-request@w3.org [mailto:semantic-web-request@w3.org]
On
Behalf Of Gong Cheng
Sent: Mittwoch, 12. Oktober 2005 16:58
To: semantic-web@w3c.org
Cc: semanticweb@yahoogroups.com
Subject: Sorry for misunderstanding my problem

Hi all,

I'm sorry I failed to express my problem.
I mean that in most ontologies I have read, only subClassOf-hierarchy
can be
found. So it seems missing lots of other relationships(I mean instances
of
ObjectProperty) between concepts in the model rather than in the real
world.
Maybe the authors and users do not need those relationships in their
views.
But it does make the model not enough perfect...
I don't know whether it is better to involve almost all the
relationships in
the specific domain, or just necessary.
I hope my poor English never bother you again...

Regards,

Gong Cheng





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