BIBO use of `rdfs:isDefinedBy`

[tombaker]

BIBO and DC Terms differ in their use of rdfs:isDefinedBy:

• In BIBO, rdfs:isDefinedBy takes a literal object of type xsd:anyURI. Example:

    <http://purl.org/ontology/bibo/numPages> <http://www.w3.org/2000/01/rdf-schema#isDefinedBy> "http://purl.org/ontology/bibo/"^^<http://www.w3.org/2001/XMLSchema#anyURI> .

• In DC Terms, rdfs:isDefinedBy takes the namespace URI of DC Terms as object. Example:

    <http://purl.org/dc/terms/format> <http://www.w3.org/2000/01/rdf-schema#isDefinedBy> <http://purl.org/dc/terms/> .

[tombaker]

The RDF Schema specification defines the range of rdfs:isDefinedBy as rdfs:Resource. However, the spec adds: "It may be possible to retrieve representations of O from the Web, but this is not required. When such representations may be retrieved, no constraints are placed on the format of those representations."

This language seems to imply that the object should not be a literal, which suggests that the DCMI style is more correct than the BIBO style.

If we decide to create a BIBO namespace document separate from the ontology, then I suggest we take the opportunity to follow DCMI style for rdfs:isDefinedBy.

The would amount to a significant semantic change to BIBO, though I'm unsure how big that change would be in practice because I am unsure who really uses rdfs:isDefinedBy and for what purposes.

[philbarker]

FWIW, both https://www.w3.org/1999/02/22-rdf-syntax-ns# and https://www.w3.org/2000/01/rdf-schema# have IRI values, e.g.

	rdfs:isDefinedBy <http://www.w3.org/1999/02/22-rdf-syntax-ns#> ;

which suggests who ever wrote the ttl serialization of rdf expected non-literals.

[niklasl]

Yes, I am quite sure that the current BIBO use of literals for rdfs:isDefinedBy is an error that should simply be fixed.

(The defining resource is the ontology, not its IRI. Tools need to be able to look up e.g. its name, publisher and other relevant metadata. In fact, I recall BIBO not doing this originally, as I did some work based on it and did look up these things back then.)