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Re: multiple-graph example in the Primner

From: Pat Hayes <phayes@ihmc.us>
Date: Sat, 7 Dec 2013 00:27:41 -0600
Cc: RDF WG <public-rdf-wg@w3.org>
Message-Id: <DAC96F45-5761-422F-8005-45B8A067E29D@ihmc.us>
To: Guus Schreiber <guus.schreiber@vu.nl>

On Dec 5, 2013, at 4:53 AM, Guus Schreiber <guus.schreiber@vu.nl> wrote:

> In the telecon yesterday there were some flames about the graph metadata examples in the Primer.
> 
> My position:
> - There needs to be at least one example triple in the Primer in which a graph name is being used. Dropping this completely is for the editors a no-go.

Including such an example is a no-go for me. I will formally object (or protest, or register a dissent, I am not sure of the exact W3C process involved here) if the WG publishes any document which implies that such usage is in any way supported by the RDF 1.1 specifications. That is *exactly* the semantic stumbling-point at which we were unable to provide any semantics for datasets. RDF 1.1 does NOT imply in any way that the use of a graph-name in an RDF triple can or should be understood to refer to the graph. On the contrary, it explicitly denies the validity of such an assumption. 

> - We are happy to consider other examples. Please suggest.
> - We're happy to include other/updated caveats
> 
> Current phrasing included below. Text suggestions very much appreciated!
> 
> Guus
> 
> From https://dvcs.w3.org/hg/rdf/raw-file/default/rdf-primer/index.html#subsection-multiple-graphs :
> 
> [[
> We can write down triples that include a graph name, for example:
> 
>  <http://example.org/bob> <is published by> <http://example.org>.
>  <http://example.org/bob> <has license>
>      <http://creativecommons.org/licenses /by/3.0/>.
> 
> These two triples could be interpreted as license and provenance information of the graph http://example.org/bob.
> 
> NOTE
> RDF does not define the way in which the graph name and the graph are related. It is therefore up to application developers to decide how to interpret such triples.

That does not deal with the central difficulty. RDF is intended for use in publishing data on the open Web. The issue involved here is, if Alice publishes an RDF dataset, and Bob reads it, how can Bob know whether a graph name used in RDF in the datset should be interpreted as referring to the graph it names? And the clear, unambiguous answer given by our RDF specs is, Bob cannot know this. There is no way specified to record or transmit this information through RDF or any means usable by an RDF engine. Alice might conform to the metadata useage needed by PROV, and Bob might read this and interpret it differently, without failing in any way to conform to RDF. So as far as RDF is concerned, this usage is invisible. Vague references to "application developers" does not deal with this issue. 

Pat

> ]]
> 
> 
> 
> 

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Received on Saturday, 7 December 2013 06:28:09 UTC

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