Re: [dxwg] Inconsistency between usage note of dcat:themeTaxonomy and range of dcat:theme? (#1153)

Thanks for pointing out the dcat:keyword property to be used with keywords. 

"It was felt that it was necessary to restrict the objects to just instances of skos:Concept."

Note, however, that the result of the range skos:Concept does not _restrict_ the objects to instances of topics previously defined as being of class skos:Concept; it has the function of inferring the class skos:Concept to any URI in the object position. (I have no idea what is inferred if the value is a string.) So if someone uses `https://en.wikipedia.org/wiki/Eiffel_Tower` as the object of dcat:theme, `https://en.wikipedia.org/wiki/Eiffel_Tower` is inferred to be a skos:Concept. The only way to restrict objects to skos:Concept is by using a validation scheme like SHACL or ShEx. That said, having the desired range be explicit in the property definition as a range is probably a better clue for metadata creators than a note on the property, but be aware that reasoners (if any are used, which often they are not) will read this differently.

This is the main reason that SHACL and ShEx were developed: RDF does no restricting, only inferring, and what metadata creators need most is some control over the content of the data, not an open world of inferences.

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Received on Tuesday, 5 November 2019 11:28:15 UTC