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Re: Defining subsets of existing OWL / RDF-S vocabularies in another vocabulary?

From: Richard Cyganiak <richard@cyganiak.de>
Date: Fri, 28 Sep 2007 13:19:36 +0200
Message-Id: <F4EFD625-1619-467C-A61E-AD36B0F5B598@cyganiak.de>
Cc: "Semantic-Web@W3.Org," <semantic-web@w3.org>, "Semanticweb@Yahoogroups.Com," <semanticweb@yahoogroups.com>, Tim Berners-Lee <timbl@w3.org>, Katharina Siorpaes <katharina.siorpaes@deri.at>
To: mhepp@computer.org


On 27 Sep 2007, at 20:21, Martin Hepp wrote:
> Dear all:
> Is it valid to locally define a subset of an existing OWL / RDF-S  
> vocabulary in your own vocabulary in order to
> a) avoid ontology imports or
> b) make it simple for annotation tools to display only a relevant  
> subset of that external vocabulary?
> In other words, can I declare some FOAF or Dublin Core vocabulary  
> elements, which are relevant for my annotation task, locally in my  
> new domain vocabulary, instead of adding an import statement for  
> the whole vocabulary in the ontology header?

Depends. If you're building a closed semantic silo system, then the  
FOAF people won't care what you do inside, and you can redefine  
anything you like as long as it works for you.

But if you exchange data with the rest of the world, then you'll have  
to keep in mind that some agents are web-aware, and will get their  
definition of foaf:name from http://xmlns.com/foaf/0.1/name, and not  
from your copy, regardless of whatever owl:imports you may have  

As long as the live spec and your copy are in sync, that's not a  
problem. Your copy is simply a partial mirror of the FOAF spec, and  
there's nothing wrong with hardcoding your system to use that mirror  
instead of the real spec. (Modulo copyright issues.)

If you really want to make sure that all agents encountering your  
data work off the same vocabulary definitions, then you should  
probably duplicate the relevant terms in your own namespace, creating  
hepp:name and hepp:knows and so on, and declare them  
owl:equivalentProperty to the original terms.


> If that was okay, it would make it easier to prepare pre-composed  
> blends of relevant ontologies that can be directly used for form- 
> based instance data creation.
> However, I fear that defining an element that is residing in  
> someone else's URI space is not okay, since I (e.g. http:// 
> www.heppnetz.de) have no authority of defining the semantics of an  
> element that is within
> |http://xmlns.com/foaf/0.1/, even if I what I am saying is  
> consistent with the authoritative definition of the given  
> vocabulary element. |
> ||
> ||I am assuming that I duplicate the very same specification of the  
> element, i.e., I would assure that my definition just replicates a  
> subset of the official vocabulary. I also abstract from semantic  
> dependencies, i.e., whether it is possible to specify a consistent  
> subset of a given vocabulary (this may not be trivial for an  
> expressive DL ontology, but should be feasible for lightweight RDF- 
> S or OWL vocabularies). Also, the legal point of view (whether I am  
> allowed to replicate an existing specification) is less relevant  
> for me at the moment. I just want to know whether this is an  
> acceptable practice from a Web Architecture perspective.
> Any feedback would be very much appreciated!
> Best
> Martin
> -----------------------------------------------------
> martin hepp
> e-mail: martin.hepp@deri.at
> web:    http://www.heppnetz.de
> skype:  mfhepp
> office: +43 512 507 6465
> Check eClassOWL, the first real-world e-business ontology
> for products and services in OWL at
> http://www.heppnetz.de/eclassOWL
Received on Friday, 28 September 2007 11:19:50 UTC

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