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Re: Labelled graphs

From: Sandro Hawke <sandro@w3.org>
Date: Sun, 15 Apr 2012 10:57:09 -0400
To: Andy Seaborne <andy.seaborne@epimorphics.com>
Cc: RDF-WG <public-rdf-wg@w3.org>
Message-ID: <1334501829.2482.13.camel@waldron>
On Sat, 2012-04-14 at 20:35 +0100, Andy Seaborne wrote:
> On 13/04/12 11:33, Steve Harris wrote:
> >> Read that as rdf:aaa to avoid natural language meaning.
> > I don't get that, but…
> 
> Natural language can be confusing.
> 
> <u> rdf:label G .
> 
> so is <u> labelled by G ?
>     "<u> has a label of G"
>     "G is a label for <u>"
> 
> or is <u> labelling G ?
>     "<u> is a label for G"
>     "G has a label of <u>"
> 
> (sometimes it does not matter -- e.g. sameValue).
> 
> "labelled graphs" is more of the style "<u> is a label of G".
> 
> All that is needed as the most basic building block is a neutral 
> association of (<u>, G) and that within a dataset (<ui>, Gi) is 
> functional from <ui> to Gi : given a label, find the associated graph.

With these looser semantics, I don't think it needs to be functional.
Rather, I think we can define it as labeling the associated graph and
each of its subgraphs.

There would be some kind of deep equivalence between these two datasets:

D1:
   <u> { <a> <b> 1 }
   <u> { <a> <b> 2 }
and
D2:
   <u> { <a> <b> 1,2 }

The SPARQL semantics might written in terms of a normal form, where a
term is only used as a label once, but the other forms would be valid in
trig and in the RDF Semantics.   

   -- Sandro
Received on Sunday, 15 April 2012 14:57:18 UTC

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