On Wed, Aug 26, 2015 at 11:44 AM, Steven Folsom <[log in to unmask]> wrote:
I’m very supportive of the authorities proposal’s attempt to decouple authorities from the entities they describe.


For example: https://viaf.org/viaf/36997809/rdf.xml has a URI for the document ("http://viaf.org/viaf/36997809/“) and another for Carl Sagan himself ("http://viaf.org/viaf/36997809”, without the trailing slash). The Person URI has sameAs assertions with both authorities and entities modeled as persons.

And thus implementers need to be careful to link to the right external URIs, but at the ontology level I think it's okay?

Re:Roles, I’m a little confused about semantics of the role proposal, 
 That bf:Contributor has a related agent. Is the bf:Contributor really more of a Contribution, like a PROV Activity (http://www.w3.org/TR/prov-o/)? If so, the proposal makes semantic sense, and I would just recommend naming bf:Contributor to bf:Contribution or just using PROV activity.

I think the use of prov:Activity here is a great suggestion and would make things both clearer, and more closely aligned with other event-based descriptions. Reusing existing ontologies, rather than reinventing everything, would be a valuable change that the proposals are edging towards, if not yet adopting wholeheartedly.

Re: the Identifiers proposal, Karen has said this before, but we shouldn’t conflate the role of URIs with string identifiers. When I read the Authorities proposal, I interpret bf:identifiedBy as having the semantics:

<some thing> <is identified through an authority> <some authority resource> .
**But** the identifier proposal says the bf:identifiedBy property is for an identifier string.
That’s very different. I would recommend we be able to say the following through different properties:
<some bf:Resource> <is described by an authority> <some authority resource> .
<some authority resource> <is identified by an identifier> <some string identifier> .

I wonder about the relationship between a (conceptual) Work and an Identifier, and a (real world) Person and the Authority.  

If the authority *describes* the person, why is that information associated with the authority and not just with the person?  On the other hand, if the authority is an existing identifier for the person, rather than a description of them, then identifiedBy makes sense to me.  The bf:Authority would play the same role as the bf:Identifier, in that it's a resource which carries a string that has been used to identify the subject of the triple.

To be more concrete:

_:work a bf:Work ;
  bf:identifiedBy [
    a bf:Identifier ;
    rdf:value "123456" ;
    bf:scheme <http://some.scheme/identifier

Seems to be the same usage as:

_:person a foaf:Person ;
  bf:identifiedBy <http://some.authority/abcdef

<http://some.authority/scheme/abcdef> a bf:Authority ;
    rdf:value "Jefferson, Thomas" ;
    bf:scheme <http://some.authority/scheme> .

(And could be easily recast into SKOS)

The difference is that the authority has been given a URI, rather than being a blank node, but I think the *relationship* between the resources is the same semantically?



Rob Sanderson
Information Standards Advocate
Digital Library Systems and Services
Stanford, CA 94305