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Re: New Proposal (6.1) for GRAPHS

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Mon, 02 Apr 2012 21:35:14 +0100
Message-ID: <4F7A0D82.6020003@epimorphics.com>
To: public-rdf-wg@w3.org


On 02/04/12 16:36, Sandro Hawke wrote:
> Maybe I can clarifying by translating this TriG document:
>
>          <u1>   {<a>   <b>   <c>  }
>
> into this English declaration:
>
>          The URI 'u1' denotes something, and that thing has exactly one
>          associated RDF Graph.   That associated RDF graph consists of
>          one RDF triple, which we can write in turtle as "<a>  <b>  <c>".

Clearer but not what I would have expected.

Why "exactly one associated RDF Graph"?

RDF is all about partial descriptions of things.

If
   <u>  { <a>   <b>   <c> . <x>   <y>   <z> . }
then
   <u>  { <a>   <b>   <c> }
and also
   <u>  { <x>   <y>   <z> . }

I guess the concrete examples will help - the choice of URI scheme for 
<u> and it's scope becomes very important.

> So, perhaps it's more clear, now.  If you merged that with another TriG
> document:
>
>         <u1>  { <a>  <b>  <d> }
>
> Then, trying to accept both documents at onces, you'd be saying:
>
>         The URI 'u1' denotes something, and that thing has exactly one
>         associated RDF graph.  In one document that associated graph is
>         claimed to be the RDF triple "<a> <b> <c>", but in another
>         document that graph is claimed to be the RDF triple "<a> <b>
>         <d>".
>
> So, in this case, you can try to merge the documents, but when you do,
> you find there is a contradiction, since there is only allowed to be one
> associated graph, but in this case there are two different ones.

Technical point: even if they unique graphs, the the right conclusion is:

<c> owl:sameAs <d>  .

unless the "{ ... }" is, say, a representation of a graph, or some other 
quoted form, and not a graph itself.

But then everything is quoted, nothing is every equal.  Workable, not a 
completely different architecture from the ground up - it's like only 
have reified statements.

	Andy
Received on Monday, 2 April 2012 20:35:51 UTC

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