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[protege-owl] Property restrictions and SWRL

Martin O'Connor martin.oconnor at stanford.edu
Tue Jan 15 09:58:04 PST 2008


Pierre Nugues wrote:

>Apparently, if a property, for instance property_1, has its range  
>restricted to one individual, through the hasValue restriction, for  
>instance individual_1, it is not possible to infer this value directly  
>in SWRL. The query property_1(?x, ?y) will not unify ?y with  
>individual_1, 
>  
>
If you have an OWL restriction (property_1 hasValue "xxx") attached to 
individual_1 you are basically saying that property_1 of individual_1 
must contain the value "xxx". However, no actual value assignment is 
made so the ontology does not contain a value for the property.

Because of the DL-safe interpretation of the SWRLTab rule engine (and 
all other SWRL engines that I know of) the atom will not bind ?y in the 
atom property_1(?x, ?y) unless there is actually a value for property_1. 
See [1] and [2] for a discussion of DL-safe rules. DL-safety is there to 
ensure decidability of inference.

>even if there are individuals that show with the  property and value in the Protégé interface.
>  
>
The interface will also not show a value for property_1 (unless you 
explicitly assigned one) so I'm not sure what you mean here.

>And if so, what is the appropriate query to get the range restriction?
>  
>
I will have TBox operators to query OWL restrictions available in a 
month or two.

>Finally, when I add a new rule, for instance through the duplication  
>of an old one, it takes a while before SQWRL recognizes it with its  
>correct name. I have to toggle a couple of times between buttons  
>before the query works. Is there a proper way to have it loaded  
>properly in the database?
>  
>
This is a known bug.

Martin

[1] http://protege.cim3.net/cgi-bin/wiki.pl?SWRLLanguageFAQ#nid9VC
[2] http://clarkparsia.com/weblog/2007/08/12/understanding-swrl-part-1/



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