Re: terminology/necessity of hydra:required

On Feb 11, 2014, at 1:09 AM, Ruben Verborgh <ruben.verborgh@ugent.be> wrote:

> HI Gregg,
> 
>> foaf:Person rdfs:subClassOf owl:Restriction [ owl:onProperty foaf:familyName; owl:cardinality "1"^^xsd:unsignedInteger ] .
>> 
>> This certainly makes the presence of familyName required, although it also has the effect of making it required on all subclasses of foaf:Person I believe.
> 
> The problem is that this changes the foaf:Person class; you don't want to do that.

Yes, that's true, but the alternative mechanism using declaring a hydra:supportedProperty is also making a universal claim on foaf:Person, which could be interpreted as meaning that any service having a foaf:Person class also has a such a supported property, although it doesn't have the same entailment consequences.

From a practical point of view, if either claim is made in a service-specific vocabulary the potential for such claims to "infect" outside uses is limited.

This also puts into question _any_ use of OWL to make claims that are service specific. In any case, a hydra:required property does overlap cardinality constraints, and if it's appropriate to duplicate such functionality in a Hydra vocabulary, perhaps it should rely on the same concepts.

>> Other properties may use owl:minCardinality instead, but that wouldn't make much sense for a family name.
> 
> Some people do have multiple family names (in different languages).

Good point.

Gregg

> But in general, it doesn't seem right to constrain an entire (cross-application) class
> for specific application functionality.
> Best,
> 
> Ruben

Received on Tuesday, 11 February 2014 17:53:03 UTC