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Re: Use case: find all the triples which do or do not use a URI from a namespace

From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
Date: Fri, 16 Apr 2004 10:24:58 +0100
To: public-rdf-dawg@w3.org
Message-ID: <20040416092458.GA21232@login.ecs.soton.ac.uk>

On Fri, Apr 16, 2004 at 10:31:24 +0300, Patrick Stickler wrote:
> On Apr 15, 2004, at 20:28, ext Pat Hayes wrote:
> >The developer wishes to be able to detect when any such triples occur  
> >in an RDF graph, to extract them all when they do occur, and also to  
> >be able to extract all triples which do not use any name in this  
> >reserved namespace. To do this, a query which matches any triple with  
> >a property name in a set of namespaces would be a useful feature, for  
> >example in an ad-hoc notation:
> >
> >(?x {+<codelay:>  +<cadegra:>}?y ?z .)
> 
> Are you refering to namespace prefixes here? How can one do this since
> (a) there are no qnames, nor namespaces, in RDF (regardless of what
> syntactic machinery might be employed in RDF/XML or any other  
> serialization
> of an RDF graph) and (b) there is no reliable way to deduce any  
> namespace
> prefix from an arbitrary URI.

That's true from the query engines persepctive, but as the author of a
query you can state that you are interested in URIs with a given prefix.
Effectivly stating that it is a namespace. From the engines p.o.v. it can
then do a substring match, RDQL it could be something like

AND ?uri LIKE <http://my.domain/namepsace#%>

with appologies ;)

- Steve
Received on Friday, 16 April 2004 05:25:13 GMT

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