Re: How burdensome are the OWL restrictions on metadata?

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 Friday, 4 April 2003 16:05:37 UTC