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BIBFRAME  January 2015

BIBFRAME January 2015

Subject:

Re: Constrained vs unconstrained schemas

From:

Gordon Dunsire <[log in to unmask]>

Reply-To:

Bibliographic Framework Transition Initiative Forum <[log in to unmask]>

Date:

Tue, 6 Jan 2015 12:41:35 -0000

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (215 lines)

All

Many applications based on RDF data will need to know what type of thing is
being described by a triple. An application can get that information
implicitly, from the domain and range of the triple's property, or
explicitly, from a separate triple stating the thing's type. There is no
guarantee that such a type triple exists, or is connected to the local
graph, or can be retrieved from the global graph.

The quality (effectiveness, efficiency, etc.) of these applications is
likely to depend on the accuracy and completeness of entity typing. More
sophisticated applications are likely to depend also on the semantic
coherence of the results of typing.

Publishers of data based on specific ontologies should be able to choose
whether to provide type triples implicitly or explicitly. Using properties
constrained by domain and range allows implicit typing by applications
intended to consume the data. The maintainers of the specific ontology are
probably the best agents to provide data publishers and consumers with the
RDF element sets for the constrained properties and, indeed, the type
classes used to constrain them.

Publishing data using constrained properties does not prevent its use by
applications that are simple, low-quality, or do not require entity typing.
Such applications may use RDF maps to dumb-down constrained properties to
unconstrained versions, or simply ignore domains and ranges. The RDF maps
may be local to the application, or provided by the maintainers of the
constrained elements or some other agent.

I agree that the publishers of library data in RDF should be able to specify
how it is intended to be used by libraries: this is a closed-world
assumption. The BF model seems to be mainly influenced by the data currently
used by library applications based on MARC21; the FRBR model reflects the
functional requirements to support world-wide consensus on user tasks. I
think both of these bases, data and users, are good indicators of the needs
of future library applications. I therefore think it is a benefit that the
BIBFRAME Initiative (BFI), IFLA, and the JSC for RDA are providing
constrained RDF element sets for BF, FRBR, ISBD, and RDA. I also think the
provision of unconstrained element sets is a good thing, together with
mappings from constrained to unconstrained properties. I do not know whether
BFI intends to publish unconstrained properties. I do know that the FRBR
Review Group decided not to do so because of its plans to consolidate the
FRBR, FRAD, and FRSAD models (now approaching completion), and that the ISBD
Review Group has an unconstrained element set ready for publication in the
near future with a corresponding map.

The JSC and ISBD Review Group have collaborated on a map between the ISBD
and RDA elements [1]. The map, based on an updated version of the agreed
element alignment [2] will be published in the next few weeks. It
necessarily uses unconstrained properties to link well-formed ISBD and RDA
data together, and was a stimulus to the development of the unconstrained
ISBD element set. As noted in the pre-print cited by Karen, there is also a
map between ISBD and FRBR classes which requires local semantics for
"aspect" relationships [3].

I am not convinced that the assumption that RDA Work and RDA Expression are
equivalent to/same as BF Work is a useful or valid one [4]. I think there
may be similar problems with RDA Manifestation, RDA Item, and BF Instance.
The ISBD/RDA experience shows that careful consideration of implicit
semantics in definitions and scope notes is required, as well as explicit
semantics in domain, range, and sub-property relationships.

So I do not advise mapping either the constrained or unconstrained RDA
properties to constrained BF properties without further clarification of the
class relationships. It is ok to map constrained BF properties to
unconstrained RDA properties. A full map between RDA and BF requires the use
of unconstrained RDA and BF properties. And, by definition, a roundtrip from
constrained to unconstrained to constrained is somewhat lossy (as well as
incoherent).

I think we need further investigation of the relationship between the
RDA/FRBR models and BF, probably best carried out by the JSC and BFI. And we
need to test interoperability using orthodox RDA and BF data. Fortunately,
we now have the beta of version 3 of RIMMF to create orthodox RDA data [5].
So perhaps we can do something useful with RDA and BF data after the
Jane-athon [6].

Cheers

Gordon

[1] http://www.rda-jsc.org/docs/6JSC-Chair-4.pdf
[2]
http://www.ifla.org/files/assets/cataloguing/isbd/OtherDocumentation/ISBD2RD
A%20Alignment%20v1_1.pdf
[3]
http://www.ifla.org/files/assets/cataloguing/isbd/OtherDocumentation/resourc
e-wemi.pdf
[4] http://www.gordondunsire.com/pubs/pres/RDAMARCBIBFRAME.pptx
[5] http://www.rdaregistry.info/rimmf/index.html
[6] http://www.rdatoolkit.org/janeathon

If it is a camel, a weasel, and a whale, then it is a cloud (inferred from
Hamlet, Act 3, Scene 2).


-----Original Message-----
From: Bibliographic Framework Transition Initiative Forum
[mailto:[log in to unmask]] On Behalf Of Joseph Kiegel
Sent: 05 January 2015 23:21
To: [log in to unmask]
Subject: Re: [BIBFRAME] Constrained vs unconstrained schemas

Thanks, this helps a lot.  I had viewed domains as more restrictive than
they are.

I agree with your larger question that we need to understand the operations
that will be performed on our data in RDF.  Perhaps we can't anticipate what
other people will do, but we should be able to specify what libraries will
do.


Joe

--------------------------------------------------
From: "Karen Coyle" <[log in to unmask]>
Sent: Monday, January 05, 2015 1:38 PM
To: <[log in to unmask]>
Subject: Re: [BIBFRAME] Constrained vs unconstrained schemas

> Joseph, You might want to look at my blog post on RDF classes:
>
> http://kcoyle.blogspot.com/2014/11/classes-in-rdf.html
>
> and the article by Baker-Coyle-Petiya
>
> http://kcoyle.net/LHTv32n4preprint.pdf
>
> 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.
>
> kc
>
>
>
>
>
>
>
>
>
>
>
> 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.
>>
>
> --
> Karen Coyle
> [log in to unmask] http://kcoyle.net
> m: +1-510-435-8234
> skype: kcoylenet/+1-510-984-3600
> 

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