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On Aug 26, 2015, at 10:13 PM, Karen Coyle <[log in to unmask]<mailto:[log in to unmask]>> wrote:



On 8/26/15 8:44 AM, Steven Folsom wrote:


Re:Roles, I’m a little confused about semantics of the role proposal, which may be related to Karen’s observation about bf:Instance data and bf:Agent data. Using the example in the proposal:

bf:contributor  [a bf:Contributor ;
        bf:role <some role resource> ;
        bf:agent <some agent resource> ].


I read this to mean some work (not represented in the example) has some bnode bf:Contributor. That bf:Contributor has a role. 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, too, am puzzled about the semantics of this. To me it says:

<some resource> <has a contributor> x
x is a Contributor
x has role <role>
x has agent <agent>

x obviously doesn't *have* an agent in the way that it has a role -- <agent> is the identifier for x. But I don't see how x can *be* both x AND some agent. In this example "x" represents the contributor, and <agent> also represents the contributor. Or, if you look at it in terms of what entity is being described, it comes down to "x has agent <x>" because they are talking about the same thing. (This seems to call for "owl:sameAs".)

I think this is one of the tricky aspects of using blank nodes. It isn't that they represent a blank -- they represent a specific thing that, at that moment in time, has no name. But it's still a thing. It's not, as it has been called here, a data structure. So the bnode x is a real thing, and if it is the same thing as <agent> then, as you say below, the most sensible way to portray this in RDF is:

<some work> <some role/relator> <some agent resource> .

or


<some bib entity> bf:contributor  [a bf:Contributor ;
        bf:role <some role resource> ;
        owl:sameAs <some agent resource> ].

I'm less inclined to use this second pattern because it's really just attributing a role to the Contributor, not necessarily a relationship between this specific Bib Entity and the Contributor.

Yes, the owl:sameAs assertion above is more semantically correct than the example in the proposal, but it further highlights that there's no need to have a bnode for Contributors. If there is a known URI for the agent at the end of that triple why have bnode at all. And/or... What's stopping us from minting a new URI locally if we know something new about <some agent resource> but can't contribute to <some agent resource>'s instance data? In the latter case we would definitely want an owl:sameAs assertion between the two URIs.



kc



If the bf:Contributor is a bf:Agent then there are some issues. The bnode bf:Contributor (again, if it is a bf:Agent) is the *same as* the <some agent resource>; the <some agent resource> isn’t the *agent of* the bnode bf:Contributor. Also, if the bnode were ever replaced by a URI for the Agent, all other roles the Agent ever performed in other works would automatically be now associated with this work.

If a bf:Contributor is a bf:Agent it would make more sense just to say:

<some work> <some role/relator> <some agent resource> .

(Note, the <some role/relator> property would have to have the range of an Agent. We would have to careful to not use properties that have domains of a work with a range of authority with bf:Contributors if they are agents.)

The Agent in turn could be described by an authority:

<some work> <some role/relator> <some agent resource> .

<some agent resource> <bf:identifiedBy> <some authority> .



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> .


Thank you for your consideration,
Steven

————
Steven Folsom
Metadata Strategist and Standards Advocate
Cornell University Library







On 8/25/15, 5:58 PM, "Bibliographic Framework Transition Initiative Forum on behalf of Thomas Berger" <[log in to unmask] on behalf of [log in to unmask]><mailto:[log in to unmask]@Gymel.com> wrote:



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Am 25.08.2015 um 19:58 schrieb Karen Coyle:



bf:contributor [
   a bf:Contributor ;
   bf:role<http://id.loc.gov/vocabulary/relators/ill><http://id.loc.gov/vocabulary/relators/ill>  ;
   bf:role<http://id.loc.gov/vocabulary/relators/aut><http://id.loc.gov/vocabulary/relators/aut>  ;
   bf:agent<http://id.loc.gov/authorities/names/1234><http://id.loc.gov/authorities/names/1234>  ;
   bf:agent<http://d-nb.info/gnd/9876><http://d-nb.info/gnd/9876>  ].

(MARC semantics: two different roles for one bibliographic
identity accounted for in different authority files)


Wouldn't it be preferable that any equivalence between agent identifie


rs


be declared outside of the instance data for a bibliographic resource?
Logically, the information that they are equivalent is not related to


a


particular bibliographic resource, but is a fact related to the agents
themselves. It should hold true for all instances.


Well, I wouldn't expect that one cataloging agency would tie its
activities to more than one authority control environment. And if,
it probably would encapsulate that into some local construction
detailing on the exact findings of the agency:

bf:contributor [
  a bf:Contributor ;
  bf:agent<http://example.com/authorities/xyz><http://example.com/authorities/xyz> ]

<http://example.com/authorities/xyz><http://example.com/authorities/xyz> [
 a schema:Person ;
 a bf:Agent ;
 rdfs:label "John Doe (1900-1983)" ;
 skos:exactMatch <http://id.loc.gov/authorities/names/1234><http://id.loc.gov/authorities/names/1234> ;
 schema:sameAs <http://d-nb.info/gnd/9876><http://d-nb.info/gnd/9876> ;
 owl:differentFrom <http://www.wikidata.org/entity/abc><http://www.wikidata.org/entity/abc>
].

But for some bibliographic aggregator who does not want to presuppose
the authority control ecosystem potential consumers of its data would
prefer I can imagine descriptions where alternative(!) identifications
for the bf:contributor are supplied. I mean, there certainly must have
been a use case when MARC's 7XX $0 was introduced as repeatable?

I'd consider this "instancial" evidence of possible identity, declaring
equivalence in the context of a bf:Agent would be a stronger statement.

BTW: Different authority control systems use rather different
vocabularies to establish cross border identification of their
resources (there seems to be a general tendency to avoid owl:sameAs,
though). Given the fact that even for simple agents like persons
the entities not always are in 1:1 correspondance (e.g. LCAuth focussing
on bibliographic identities, and ULAN very much on real persons),
could or should there be a bf:identicalTo property declaring equivalence
in a Bibframe sense? Or would identity rather be something to be
defined by the application, e.g. data created in the context of a
manuscript and letters application would probably not distinguish
between Ruth Rendell and Barbara Vine and thus would use "regular"
authority control with a deviant notion of equivalence ;)




(This brings up the question of usage of VIAF identifiers in the place
of specific authority control identifiers, but that's another topic.)


Maybe not at all. Certainly VIAF is lacking some features we are
accustomed to find in more traditional authority control systems,
but if some people successfully start to use VIAF in lieu of
ordinary authority control, then my expectation on Bibframe would be
that VIAF based authority control should not work differently from
ordinary ones. So "VIAF" could serve as kind of litmus test for
Bibframe concepts ans properties - if they rely on "traditional"
features not present in VIAF they are lacking universality (in the
universe Bibframe is concerned with) and should be considered optional
at most.

viele Gruesse
Thomas Berger
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Karen Coyle
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