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Re: Restricted Metadata Inheritance by Named Graphs?

From: Steffen Staab <staab@uni-koblenz.de>
Date: Thu, 03 Dec 2009 10:33:41 +0100
Message-ID: <4B1785F5.9050203@uni-koblenz.de>
To: Christoph LANGE <ch.lange@jacobs-university.de>
CC: Semantic Web <semantic-web@w3.org>
Hi Christoph,

I think that you deal here with two different problems:

One problem is that you may want to "copy" / "inherit" / "whatever you 
call it" data. You can use rules for this, we use Networked Graphs:
http://west.uni-koblenz.de/Research/systeme/NetworkedGraphs

The second problem is a general one in the semantic web, namely that the
combination of data from different sources (with different trust values)
may lead to inconsistencies or propositions of varying trust values.
Here is a paper you might want to read:
Schenk, Simon (2008): On the Semantics of Trust and Caching in the 
Semantic Web. In: ISWC2008: 7th International Semantic Web Conference.

Cheers
Steffen

Christoph LANGE schrieb:
> Dear all,
> 
>   in certain knowledge bases I have encountered metadata inheritance -- one
> resource A pointing to another resource B, saying "inherit B's metadata".  So
> far, there knowledge bases have not yet assumed an RDF semantics for their
> metadata, but I'd be interested in changing that.  Now I wonder how to
> appropriately represent this kind of inheritance.
> 
> In the original application, the metadata of a resource are a fixed record
> attached to the resource.  The metadata are mostly literal-valued (Dublin Core
> and similar), but some are also URI-valued, pointing to other resources.
> 
> A na´ve approach to inheritance would be a rule
> 
> {  ?resource :inheritsMetadata ?otherResource .
>    ?otherResource ?property ?value . }
> =>
> { ?resource ?property ?value. }
> 
> This would, however, easily cause trouble in an RDF world, as
> 
> 1. the two resources might be of different types, which might be disjoint in
>    an OWL ontology, but what if ?resource inherits rdf:type from
>    ?otherResource ?
> 2. what if an inherited property is an OWL FunctionalProperty but has
>    different values on ?resource and ?otherResource ?
> 3. what if the metadata explicitly stated in the scope (e.g. the same XML
>    document) of ?otherResource are fine, but somebody else externally writes a
>    triple ?otherResource :evilProperty "value" ?
> 
> I consider (3) the most serious problem.  A solution might be named graphs.
> I.e. the metadata that the author of ?otherResource explicitly provided, and
> that (s)he considers safe, would be put into a named graph G, and the
> :inheritsMetadata property would not point to ?otherResource but to G.
> 
> Has that problem ever been dealt with?  Is there any publication/specification
> that you could recommend me to read?
> 
> Cheers, and thanks in advance,
> 
> Christoph
> 
Received on Thursday, 3 December 2009 09:34:04 GMT

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