On 6/22/15 2:24 PM, Godby,Jean wrote:
> *Questions and minor issues*
>   * ​How are the properties partitioned among 'Instance and 'Item'?
>     The example described in the Proposal document implies that the
>     'Item' class contains only properties indicating uniqueness --
>     such as shelf location, bar code, etc -- while Instance would
>     contain properties such as 'contributor,' 'creation date,' and
>     'custodial history.' Is this correct? Or is there any bleeding
>     between the Instance/Item line? For example, can an Item have an
>     author or title, or is that information always maintained in the
>     corresponding Instance description?
Jean and Jeff,

Great, and deep, analysis.

As to the above, Iactually see this as more than a minor issue (and I 
suppose you meant it as a question). This concept of a kind of "daisy 
chain" of bibliographic levels was introduced in FRBR, but FRBR was 
conceptually modeling a database design, not RDF. Folks often talk about 
"inheritance" between, say, works and instances and items, but in fact 
there is no inheritance in RDF. (There is in object-oriented 
programming, which may be why people assume that it exists here.) Given 
that RDF is kind of like disconnected bits of DNA that you hope will all 
be there where you go looking for them, I see a danger in relying on a 
graph two or three "links" away for essential information.

I don't see why there cannot be a direct relationship between items and 
authors. It could be just another set of graph relationships to the same 
resources, or a shared identifier for the item/instance/work "package". 
For some materials, e.g. art works or museum pieces, the item will be 
the main focus of information and the separation into work/instance/item 
may not be worth the costs.


Karen Coyle
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