Joseph, You might want to look at my blog post on RDF classes:
and the article by Baker-Coyle-Petiya
There are actually no "constraints" in RDF, just potential inferences.
The inferences are based on the stated domains and ranges of the
properties. There are examples of this in the Baker et al article using
RDA, FRBRer and BIBFRAME. There is no conflict with a subject being
inferred as being an instance of more than one class as long as the
classes themselves are not declared as disjoint. (The article explains
this better than I can in an email. ) The documentation for RDA,
BIBFRAME and FRBRer all presents classes as determinants of data
structure. This, to me, is a common error in RDF development. That any
subject can be an instance of more than one class is necessary for the
RDF graph's flexibility, and should be proof that classes do not
constraint your data to a single graph structure.
The declared domains of properties only come into play if inferencing is
applied. A big question, therefore, is whether any inferencing will be
done at all over the data. The utility of, for example, the RDA classes
to me is that it allows you to do simple queries for categories of
triples, e.g. "give me all of the work triples for the manifestation
with this ISBN." Other than that you can ignore the fact that domains
have been declared if they don't serve your needs.
Your question, however, brings up a much larger question that I haven't
seen discussed anywhere, which is: what kinds of operations do we expect
to perform over library data in RDF? That question really should be
answered before domains and ranges are defined, because that is the
function of those capabilities of RDF.
On 1/5/15 12:52 PM, Joseph Kiegel wrote:
> A comparison of BIBFRAME and RDA in RDF (referred to below as RDA), in
> an attempt to map RDA to BIBFRAME, raised the issue of constrained vs
> unconstrained schemas.
> The full set of RDA properties is constrained by the RDA classes of
> Agent, Work, Expression, Manifestation and Item. That is, each
> property is related to a specific class when appropriate: e.g.
> abridgementOfExpression and abridgementOfWork. A parallel set of
> properties has been created where the constraints of class are
> lifted: e.g. abridgementOf. This unconstrained version of RDA loses
> the context of some properties but is intended to facilitate mapping
> to schemas that do not use the FRBR model underlying RDA.
> BIBFRAME is a constrained schema, but constrained by different
> classes: Agent, Work, and Instance. There is no unconstrained version
> of BIBFRAME.
> A mapping of RDA to BIBFRAME presents choices and challenges.
> Is it better to use constrained RDA, which causes explicit conflicts
> of domain: e.g. mapping rdam:reproductionOfManifestation to
> bf:reproduction and rdai:reproductionOfItem to bf:reproduction?
> Or is it better to use unconstrained RDA, which still has conflicts
> (an unconstrained domain vs a constrained one in BIBFRAME): e.g.
> mapping rdau:reproductionOf to bf:reproduction?
> It is not obvious which is the better choice. Although perhaps we
> need both mappings, each with its own problems regarding original and
> destination domains.
> A corollary of the question is that any roundtrip RDA -> BF -> RDA is
> lossy. If constrained RDA is used as a starting point, RDA classes are
> lost in the mapping itself, and if unconstrained RDA is used, classes
> are lost prior to mapping. Either way, RDA classes cannot be recovered
> in a BF -> constrained RDA mapping.
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