Re: Nested supportedProperty

On 12/18/2014 9:22, Markus Lanthaler wrote:
> What exactly do you mean by global range/domain? 

The rdfs:domain (and schema:domainIncludes) statements are global in a 
sense that they do not depend on the context of a class.

>> 2) Define an abstract superclass and use inheritance
>>
>>       schema:email rdfs:domain schema:ThingWithEmail
>>       schema:Person rdfs:subClassOf schema:ThingWithEmail
>>       schema:Organization rdfs:subClassOf schema:ThingWithEmail
> Yeah.. that's the "traditional" way of doing it.. it normally introduces
> quite a lot of "artificial" classes which are only there due to those
> modeling constraints and I'm not entirely sure what you gain by that

You gain that you don't need a notion of global constraints, and 
properties no longer have to be stand-alone entities. This means that 
you have better interoperability between RDF and other languages such as 
OO systems (and even XML) where all properties are locally scoped to 
classes. This in turn reduces the learning curve, creates more direct 
mappings and round-tripping (e.g. think about all those Java class 
generators from ontologies).

> And what prevents you from doing that with global properties?

Nothing, but why invent a new concept (global properties) that is not 
supported anywhere else than in RDF? Global constraints are too limiting 
in their expressivity, e.g. they don't easily allow you to reuse the 
same property in different classes (see current threads on the 
schema.org mailing list). Furthermore, by always creating superclasses 
you just need a single mechanism to understand the constraints: just 
walk up the class hierarchy. In the current OWL world, you would need to 
check both for local owl:Restrictions (walking up the class tree) *and* 
look for global rdfs:ranges. This makes all algorithms more 
complicating. And in many (if not most) cases, a property has a single 
natural class to attach to, so my example of introducing an abstract 
superclass for emails was already quite complex.

Regards,
Holger

Received on Wednesday, 17 December 2014 23:44:08 UTC