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On 3/31/15 10:22 AM, Joseph Kiegel wrote:
> I agree with your point about strings vs identifiers in RDA.  
> Depending whether rdaw:mediumOfPerformance contains a URI or a 
> literal, it must be conditionally mapped to bf:musicMedium or 
> bf:musicMediumNote.
>
> However, while BIBFRAME properties have their ranges set either to a 
> literal or a URI, the paired properties needed to cover both cases are 
> not always defined.  For example, for rdam:mediaType, rdam:carrierType 
> and rdae:contentType, the value may be either a literal or URI under 
> RDA.  Of course, we would prefer URIs in linked data.  On the BIBFRAME 
> side, the corresponding properties are mediaCategory, carrierCategory 
> and contentCategory, all of which have a range of bf:Category.  Of the 
> properties with a domain of bf:Category, we have only bf:categoryValue 
> in which to put a value, and its range is a literal.  There is no 
> bf:categoryUri with a domain of bf:Category and a range of 
> rdfs:Resource, which is needed to contain category values when they 
> are URIs.

Joe, this is what I think BF tries to solve by using blank nodes. A 
blank node is a URI (it's just a funny kind of URI). So if you have a 
string, you do something like:

ex:A bf:propertyThatRequiresURI _:blankNodeURI
_:blankNodeURI bf:label "The string"

OK, that's a pretty poorly done example, but I think you get the point.

The down side of this is that blank nodes do not play well on the open 
web. They are fine for your local data store, but you aren't going to 
get much use out of them in the LOD space. So it seems to me that we 
need a profile of RDA that gives the cataloging rules for linked data -- 
that is, if you are intending to create linked data, you do not get a 
choice between a string and a URI. RDA attempts to be all things to all 
cataloging needs, but any single metadata environment is usually more 
precise. We can think of RDA as the biggest pool from which specific 
rules can be selected, just as one can select from RDA the core elements 
only; or see it as a set of rule interpretations for linked data cataloging.

Nothing else really is going to work. This is why I think that between 
tech development and cataloging rules we need a kind of iterative 
development. Developing them in separate closed environments cannot 
possibly work because they have to work together.

kc

>
> The same thing is true with identifiers in BIBFRAME.  Conceivably, you 
> could decompose identifier URIs into bf:identifierScheme (range: 
> rdfs:Resource) and bf:identifierValue (range: rdfs:Literal), but that 
> is doing it the hard way.  It would be better to have a property 
> bf:identifierUri with a domain of bf:Identifier and a range of 
> rdfs:Resource, which could contain an identifier expressed as a URI.  
> As it stands now, even bf:uri has to have a literal as its value.
>
>
> Joe
>
> --------------------------------------------------
> From: "Karen Coyle" <[log in to unmask]>
> Sent: Saturday, March 28, 2015 7:05 AM
> To: <[log in to unmask]>
> Subject: Re: [BIBFRAME] BIBFRAME and RDA/RDF
>
>> Joseph, thanks for doing a comparison. Note that BF has about 400 
>> properties, while RDA has nearly a thousand, so it is true that RDA 
>> is more detailed that BF. However, RDA has virtually no class 
>> relationships -- it's essentially a flat data space. This will have 
>> implications for the use of RDA in actual systems, since class 
>> relationships help you do things like "search all properties in the 
>> title class."
>>
>> On 3/27/15 8:04 AM, Joseph Kiegel wrote:
>>>
>>>
>>> Identifiers:
>>> Under the influence of MARC, BIBFRAME has a large set of properties 
>>> for identifiers while RDA is limited.
>>
>> The RDA rules often allow either strings or identifiers. RDA in RDF 
>> is essentially silent in most cases on whether the value for a 
>> property is expected to be a string or an identifier, and therefore 
>> it can presumably be either. This, however, is highly problematic 
>> when working with RDF data. In general, it's never good to not know 
>> what kind of data to expect for a field in your metadata -- it 
>> complicates input interfaces and the programs that use the data. 
>> However, if you want to have the possibility in your data to 
>> accommodate both strings and identifiers, you are kind of forced to 
>> create different properties for those different choices, which would 
>> mean nearly doubling the number of RDA properties. Although I find 
>> the use of blank nodes in BF to be a complicating factor, I assume 
>> that in many cases those blank nodes are there as a way around this 
>> string-vs-identifier problem, allowing each statement to point to a 
>> blank node that can have either or both.
>>
>> To me this is evidence that we need to re-iterate back from our 
>> attempts to create a viable RDF version of library data to the 
>> cataloging rules, and create at least a subset of the rules that can 
>> support a viable data format with clearly defined data values for 
>> each property. The "string or identifier" in the rules just isn't 
>> workable in a data format.
>>
>> kc
>>
>>>
>>> Subjects:
>>> RDA is not yet able to express subject relationships (RDA chapters 
>>> 33-37) and BIBFRAME has a mechanism for this.
>>>
>>> Holdings Information:
>>> Although not fully elaborated, BIBFRAME has properties for holdings 
>>> information while RDA has almost nothing.
>>>
>>>
>>> RDA is richer than BIBFRAME
>>>
>>> Series:
>>> RDA provides properties for all parts of series statements, while 
>>> BIBFRAME has a single property:  series.
>>>
>>> Notes:
>>> RDA has more properties for specific types of notes.  While BIBFRAME 
>>> has note properties, the term "note" in a property name may mean 
>>> simply that its range is a literal, e.g. findingAidNote, 
>>> musicMediumNote.
>>>
>>> Technical Details of a Resource:
>>> RDA has a large number of properties for technical details of 
>>> resources such as polarity, playingSpeed, fileSize, etc.  It is not 
>>> clear how BIBFRAME handles this type of information.
>>>
>>> Inverse Properties:
>>> RDA provides inverse properties (e.g. animator and animatorOf) while 
>>> BIBFRAME lacks them.
>>>
>>>
>>
>> -- 
>> Karen Coyle
>> [log in to unmask] http://kcoyle.net
>> m: +1-510-435-8234
>> skype: kcoylenet/+1-510-984-3600
>>

-- 
Karen Coyle
[log in to unmask] http://kcoyle.net
m: +1-510-435-8234
skype: kcoylenet/+1-510-984-3600