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Re: mergeg in current Semantics ED

From: Pat Hayes <phayes@ihmc.us>
Date: Thu, 7 Mar 2013 14:51:35 -0600
Cc: Antoine Zimmermann <antoine.zimmermann@emse.fr>, RDF WG <public-rdf-wg@w3.org>
Message-Id: <5869AFFE-8DA1-43B7-95CC-3667640FF590@ihmc.us>
To: Peter Patel-Schneider <pfpschneider@gmail.com>

On Mar 7, 2013, at 12:30 PM, Peter Patel-Schneider wrote:

> 
> 
> On Thu, Mar 7, 2013 at 10:22 AM, Pat Hayes <phayes@ihmc.us> wrote:
> 
> On Mar 7, 2013, at 9:52 AM, Antoine Zimmermann wrote:
> 
> > There is a problem with the definition of merge in the draft.
> >
> > I'm using math notations instead of a concrete serialisation syntax because I want to show things at the abstract syntax level, which is what RDF Semantics relies on.
> >
> > Let us take a blank node b from the set of blank nodes. Let us consider the two graphs G1 = {(<s1>,<p1>,b)} and G2 = {(<s2>,<p2>,b)}.
> 
> You have the same bnode in both graphs, so they must be in the same scope, right? For example, both are subgraphs of a larger graph, or both in the same dataset.
> 
> >
> > Let us ask ourselves whether {G1,G2} entails:
> >
> > G = {(<s1>,<p1>,b),(<s2>,<p2>,b)}
> >
> > The answer is trivially NO wrt the current semantics of the ED.
> 
> If those really are the same b, then the answer is YES, and I claim that it should be.
> 
> 
> I don't know how you are going to get this to go through.

Do you mean, technically or politically? Technically, this is true now (that G1 and G2 together entail G) and it also was in the 2004 semantics, if the G1 and G2 were for example subgraphs of G. Politically, I think we have debated this to death and the new account based on scopes is exactly what the WG wants. For example, we have an explicit decision that all bnodes in (all graphs in) a dataset shall share bnodes in common, so to standardize those bnodes apart would be definitely a mistake. 

Pat


> 
> peter
>  
> 

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Received on Thursday, 7 March 2013 20:52:05 GMT

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