Re: Asserting subclasses of open ranges or domains

On 8 Sep 2009, at 10:03, Bernard Vatant wrote:

> - Are such constructions valid in RDFS and/or OWL?
> - Are they useful?


I think they're valid, but I don't think they're especially useful.

Given:

	dcterms:subject rdfs:range _:b .
	skos:Concept rdfs:subClassOf _:b .
	foaf:Person rdfs:subClassOf _:b .
	<doc> dcterms:subject <#thing> .

what useful conclusions can a reasoner come to? It can't conclude  
that <#thing> is a foaf:Person; it can't conclude that <#thing> is a  
skos:Concept; in fact, <#thing> might be neither of those - it could  
be anything.

A related OWL construct is:

	ex:subject rdfs:range _:b .
	_b: owl:unionOf ( skos:Concept foaf:Person ) .
	
Where the reasoner could at least conclude that if <doc> ex:subject  
<#thing> then <#thing> must be either a skos:Concept or a foaf:Person  
or both. This is more useful for reasoning with, because combined  
with a few other inferences it could narrow down <#thing>'s class.

OK, given that your original example is not much use to automated  
reasoners, could it at least be helpful to humans reading the schema?  
Yes, perhaps, but it's likely they'd be served better by text written  
in natural language - a rdfs:comment, skos:note, etc.

-- 
Toby A Inkster
<mailto:mail@tobyinkster.co.uk>
<http://tobyinkster.co.uk>

Received on Tuesday, 8 September 2009 10:00:00 UTC