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More on disjointedness

From: Karen Coyle <kcoyle@kcoyle.net>
Date: Fri, 25 Nov 2011 18:16:24 -0800
Message-ID: <20111125181624.185726bqeh8hbh14@kcoyle.net>
To: public-lld <public-lld@w3.org>
Sorry to go back to this, but I keep ruminating on it because there  
are things I haven't understood yet.

In FRBRer each property is given a rdfs:domain designation of the  
FRBRer class to which it belongs. This follows what I read as the  
intent of the FRBR model, which is that it creates a bibliographic  
universe where each entity has a set of properties ("attributes" in  
the FRBR doc), and each property describes one and only one entity.

Given this use of the rdfs:domain property, I'm not sure how much more  
constraint is added by the declaration of the classes being disjoint.  
In the context of FRBRer, it seems redundant. I can see where  
"disjoint" would affect the creation of properties, since it would  
mean that no property could have more than one FRBRer class as  
rdfs:domain, but since FRBRer is being defined by the FRBR group and  
only the FRBR group, any new properties being created will follow this  
"one-to-one" principle.

I asked about examples of where this disjointedness would make a  
difference. Dan Brickley's answer[1] seems not to answer the question  
because it doesn't use FRBRer properties, but if it did, it would be  
the domain declaration on the property that is violated, not the  
disjointedness of the classes. No?

RDA runs into a problem that might be a better example: it wants to  
create some data elements that can be used with any entity. These are  
mainly administrative data elements, such as cataloger's notes about  
the cataloging decisions made during the creation of the data. They  
are not properties that are defined in FRBR/FRBRer. If RDA creates  
these properties and does NOT constrain them to a FRBRer domain  
(perhaps leaving them domainless), would using these properties in  
statements describing FRBRer entities violate the "disjoint" constraint?

I'll try to do an example:

_xyz: a FRBRer:Work
     RDVocab:workTitle "Little Women"
     RDVocab:catNote "something something"
_abc: a FRBRer:Expression
     RDVocab:languageOfExpression "English"
     FRBRer:isRealizationOf _xyz
     RDVocab:catNote "something about the expression"

   RDVocab:workTitle has rdfs:domain FRBRer:Work
   RDVocab:languageOfExpression has rdfs:domain FRBRer:Expression
   RDVocab:catNote has no rdfs:domain defined

I believe that another way to pose this question is whether the use of  
rdfs:disjoint constrains extension of FRBRer by users of other  
namespaces. It seems that it would disallow defining a property as  
having more than one FRBRer rdfs:domain declaration, but does it have  
other implications as well?


[1] http://lists.w3.org/Archives/Public/public-lld/2011Nov/0006.html

Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
ph: 1-510-540-7596
m: 1-510-435-8234
skype: kcoylenet
Received on Saturday, 26 November 2011 02:16:56 UTC

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