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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

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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
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> 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
>