[Pellet-users] Simple problem with rule

[Evren Sirin]

On 11/2/07 5:39 AM, Matt Williams wrote:
> Dear All,
>
> I have an ontology with a simple rule:
>
> Women(x) -> Men(x)
>   

This SWRL rule is equivalent to saying that Women is subClassOf Men.
> which I think I have expressed below in SWRL syntax (at the end of message)
>
> Since Men & Women are disjoint, this should result in the ontology 
> becoming inconsistent, 

No, this axiom combined with the above rule would only cause the concept 
Women to be unsatisfiable. Having an unsatisfiable class in an ontology 
does not make the ontology inconsistent. Defining an instance for an 
unsatisfiable concept makes the ontology inconsistent.

However, with Pellet, you wouldn't still get the inference that Women is 
unsatisfiable because Pellet supports only DL-safe rules. DL-safety 
means that the rules only apply to the named individuals. See Bijan's 
SWRL series that explains SWRL and DL safety in depth:

http://clarkparsia.com/weblog/category/semweb/rules/swrl/

> and I have checked this by asserting that the 
> only individual in the ontology who is a woman is also a man; when I do 
> this, pellet obviously says that it is inconsistent.
>   

Yes, this is what is supposed to happen with both standard SWRL 
semantics and DL-safe semantics.

> However, just using the rule leaves the ontology as being consistent, 
> which suggests that either the rule isn't firing or something else.
>   
> Any ideas? (I suspect there is a bug in the rule, but I can't see it)
>   

There is no problem with the rule. Hope the above explanation makes it 
clear.

Cheers,
Evren
> Thanks a lot,
>
> Matt
>
>
>
>
>
> <swrl:Variable rdf:about="#x"/>
>
> <swrl:Imp rdf:about="#OSSep">
>
> <swrl:head rdf:parseType="Collection">
> <swrl:ClassAtom>
> <swrl:classPredicate rdf:resource="#Men"/>
> <swrl:argument1 rdf:resource="#x"/>
> </swrl:ClassAtom>
> </swrl:head>
>
> <swrl:body rdf:parseType="Collection">
> <swrl:ClassAtom>
> <swrl:classPredicate rdf:resource="#Women"/>
> <swrl:argument1 rdf:resource="#x"/>
> </swrl:ClassAtom>
> </swrl:body>
>
> </swrl:Imp>
>
>
>
>
>