Re: Comments on yesterday's version of the fresnel document

From: Emmanuel Pietriga <>
Date: Thu, 24 Mar 2005 19:13:09 +0100

Chris Bizer wrote:
>>>Another advantage is that using this explicit distinction, we can also
>>>display RDF schema information and OWL ontologies, which we cann't if
>>>the browser automatically infers the instances. Right?
>>I don't see why. Suppose you want to visualize an RDF schema. You
>>probably want to define a lens for resources representing classes,
>>another one for resources representing properties. These are
>>respectively typed as rdfs:Class and rdf:Property.
>>So you would just have:
>>lensForClasses rdf:type fresnel:Lens ;
>> fresnel:lensDomain rdfs:Class .
>>lensForProperties rdf:type fresnel:Lens ;
>> fresnel:lensDomain rdf:Property .
> This brings us to the interesting topic of inference. Your approach works if
> the browser doesn't do subclass inferencing. If it does then your lens would
> apply to all typed instances in the dataset.

"Instances" in the context of a model that mainly uses RDFS terms to
describe an RDF vocabulary (which is the example we are talking about
here), are actually resources that represent classes and properties. So
I don't see any problem with that. That is what is intended. But we are
playing woth various levels of abstraction here. That's fun, but it is
not easy to discuss by email. So I'm probably missing something.

What is bothering you?

> There are arguments for both approaches.
> 1. If the browser does interencing, then a fresnel:lensDomain foaf:person
> lens would apply to all instances of foaf:Person and subclasses of
> foaf:Person.

We are leaving this RDFS model styling here. But yes, you are right.

> You would have to use instanceDomain to explicitly state that
> you want to display classes as instances.

I don't understand. Why in this context would you want to display
classes? We are out of this RDFS model if you are talking about styling
foaf:Person instances.

> 2. If the browser doesn't so inferencing, then your solution would work for
> direct subclasses of rdfs:Class but not for deeper subclasses.


> I would prefer the first approach. What do the others think?

I expect the browsers to do subclass inferencing. I would like you to
explain what is wrong though (note that we are heading toward keeping
this explicit distinction between class and instance domains, so we
might leave this discussion for another time if you'd rather concentrate
on finalizing the vocabulary).

Emmanuel Pietriga
INRIA Futurs - Projet In Situ    tel : +33 1 69 15 34 66
Bat 490, Université Paris-Sud    fax : +33 1 69 15 65 86
91405 ORSAY Cedex FRANCE
Received on Thu Mar 24 2005 - 18:13:14 EST

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