Re: How burdensome are the OWL restrictions on metadata?

----- Original Message -----
From: "Yuzhong Qu" <yzqu@seu.edu.cn>
To: "Bob MacGregor" <macgregor@ISI.EDU>
Cc: <www-rdf-logic@w3.org>
Sent: Saturday, April 05, 2003 5:38 PM
Subject: Re: How burdensome are the OWL restrictions on metadata?


> Just curious: is system:IconClass an rdfs:subClassOf  or an instance of
rdfs:Class?

Its a subclass.  One could have made rdfs:Class the
domain of 'hasIcon', but then every class would
inherit that slot.  We only want some classes to
inherit the slot.  Protege handles metaclasses (and
metaslots, which we also use) effortlessly.

>
> Suggested as follows:
>
> system:IconClass rdf:type rdfs:Class  <!-- Should be modified  -->
> system:hasIcon rdfs:domain system:IconClass
> system:hasIcon rdfs:range xsd:string
> chime:Aircraft rdf:type system:IconClass <!--Must be modified -->
> chime:Aircraft  system:hasIcon "htttp:/localhost/.../aircraft.gif"
>
>
> Yuzhong Qu
>
>
> > At 11:11 -0800 4/4/03, Bob MacGregor wrote:
> > >Our applications like to associate icons (gifs) with some
> > >classes.  We implement this by having a class  IconClass that
> > >is a subclass of rdfs:Class that has a slot 'hasIcon'.  For example:
> > >
> > >     system:IconClass rdfs:subClassOf  rdfs:Class
> > >     rdfs:domain system:hasIcon system:IconClass
> > >     rdfs:range system:hasIcon xsd:string
> > >     chime:Aircraft rdfs:subClassOf  system:IconClass
> > >     chime:Aircraft  system:hasIcon "htttp:/localhost/.../aircraft.gif"
> > >
> > >My question is, suppose we add some statements that include
> > >some simple OWL-lite properties.  Does the combination of
> > >our meta-level statements and the OWL-lite statements land
> > >us into OWL-full, or are we OK?
> > >
> > >Cheers, Bob
> >
> > welcome to OWL Full.  That said, there are some well know tricks for
> > dealing iwth this, in particular to create a distinguished instance
> > associated with each class - the problem is you must use an
> > "extralogical" trick for managing these, as they cannot be directly
> > associated with the class -- in some of the OWL Lite ontologies we've
> > done, we create a FooData class for every class Foo (with one
> > instance which is the "noninherited properties" as they would be in
> > LOOM), and then just have our tools know about that.  The OWL design
> > requires a strict separation of datatype and objectType which is, in
> > practice, one of the main differences between OWL Lite/DL and OWL
> > Full.  If we'd decided to include some standard mechanism in the OWL
> > design for this, I think we would have been better off (i.e. almost
> > every real world system needs some way to put some kind of property
> > on each class for managing things) - but there was no consensus in
> > the group as to how and whether to do this, so it didn't make it into
> > the langauge.  My group ended up going through a bunch of the papers
> > to appear in the DL Handbook, and discovered this distinguished
> > instance trick - so that's what we are using.
> >   -JH
> > p.s. to see this used in practice, see
> > http://www.mindswap.org/2003/CancerOntology/ which is in (nearly
> > correct) Owl Lite - needs a couple minor fixes to conform to last
> > minute WG changes.  It is the largest OWL Lite (and possibly largest
> > DAML or OWL) ontology composed to date - and it uses this trick
> > because each class needs to have a lot of individual/non-inherited
> > properties attached to it.
> > --
> > Professor James Hendler   hendler@cs.umd.edu
> > Director, Semantic Web and Agent Technologies   301-405-2696
> > Maryland Information and Network Dynamics Lab.   301-405-6707 (Fax)
> > Univ of Maryland, College Park, MD 20742   240-731-3822 (Cell)
> > http://www.cs.umd.edu/users/hendler
> >
> >
> >
>

Received on Sunday, 6 April 2003 01:16:50 UTC