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Re: some GRAPHS strawpolls for today (agenda?)

From: Pat Hayes <phayes@ihmc.us>
Date: Sat, 28 Apr 2012 10:57:00 -0500
Cc: public-rdf-wg <public-rdf-wg@w3.org>
Message-Id: <0E115B66-F7C7-4FF0-835D-F0D96CDB91B2@ihmc.us>
To: Sandro Hawke <sandro@w3.org>

On Apr 25, 2012, at 9:08 AM, Sandro Hawke wrote:

> If we're going to talk about graphs today, maybe we can do it in a
> series of decisions.   There's not enough notice to make these binding,
> of course, but maybe we can get a sense of how close we are to
> consensus.
> If we can't even get consensus on a few of these, these I think we
> should stop working on graph semantics in this WG.  I hope we're very
> close to consensus on all of these, except maybe the last, which I could
> see continuing as an open issue well into CR.

As I see it, there are two "models" for this whole issue on the table. In yours, a dataset is effectively a graph-baptism device for attaching names to graphs. In the other, the term "graph name" is a misnomer, and the fourth field is more like a context or 'extension' name, in any case one which can influence the interpretations of the IRIs in the graph. Call these respectively the Name and Context views. Then different views give different votes.

> I've erred on the side of brevity here.
>     -- Sandro
> ====================================
> 1. The default graph is asserted
>  "{<a> <b> <c>}" entails turtle("<a> <b> <c>")

agree (in both views)

> 2. Named graphs are not asserted
>  "<u> {<a> <b> <c>}" does not entail turtle("<a> <b> <c>")

Name; agree.  Context: disagree

> 3. Named graphs are opaque
>  "<u> {<a> <b> <c>}"  does not entail "<u> {<a> <b> _:x}"

Name; agree.  Context: disagree.  Answer should align with 2. 

> 4. Graph labels denote just like in RDF
>  "{<u1> owl:sameAs <u2>} <u1> {<a> <b> <c>}"
>  owl-entails
>  "<u2> {<a> <b> <c>}"

Name; agree.  Context: disagree, would be my vote. But it is not crucial either way.

> 5. Blank nodes labels have file scope
>   See SPARQL queries in 
>   http://www.w3.org/2011/rdf-wg/wiki/Graphs_Design_6.1#Blank_Nodes
>   or Skolemization example in
>   http://lists.w3.org/Archives/Public/public-rdf-wg/2012Apr/0132.html

Name; agree.  Context: probably shouldn't allow blank nodes to denote contexts. (The resulting reasoning patterns are nightmarish.)

> 6. In trig, @union can be used in place of the default graph
>   "@union <u> {<a> <b> <c>}" entails turtle "<a> <b> <c>"

? I don't know what this is supposed to mean, I confess. 

> 7. Datasets only say which triples are known to be in a named graph,
>   not which triples are *not* in that named graph.

Name: strongly disagree.  Context: agree


>   The merge of "<u> {<a> <b> <c>}" and "<u> {<a> <b> <d>}" is 
>   "<u> {<a> <b> <c>,<d>}".  
>   Also "<u> {<a> <b> <c>,<d>}" entails "<u> {<a> <b> <c>}".

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Received on Saturday, 28 April 2012 15:57:33 UTC

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