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Re: Draft for a "minimal dataset semantics"

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 12 Sep 2012 22:11:07 -0500
Cc: Antoine Zimmermann <antoine.zimmermann@emse.fr>, RDF WG <public-rdf-wg@w3.org>
Message-Id: <C4400917-7366-4551-B409-07B458980BAF@ihmc.us>
To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>

On Sep 12, 2012, at 8:08 PM, Peter F. Patel-Schneider wrote:

> I don't think that example 2.16 is correct.
> 
> It seems to me that any dataset with a consistent default graph is consistent.

Yes, I agree. 
> 
> Any interpretation of the default graph can be extended to an interpretation of the dataset by mapping every resource to inconsistent graphs.   This trivially satisfies "IGEXT(/I_d /(/n/)) is defined and /E/-entails g" as an inconsistent graph entails every graph.

Right.

> 
> I don't think that this means that 2.16 is not tricky.  There is some interaction.  However, this means that named graphs are not independent from each other.  In fact, there is a much easier situation showing that named graphs are not independent, namely 2.13 T11.2  Similarly, it means that named graphs are not independent from the default graph.

The term "independent from" is not defined anywhere, and I think whatever Antoine meant by it is not what you mean by it. Lets just stick to the actual entailment examples. 

BTW, as I read these examples, it means that entailments are affected by the default graphs in *other* datasets. So for example 2.13 T11.2 could be an entailment from two datasets to a third dataset, right? Not (just) an entailment from one dataset with two graphs to another dataset with three graphs.

> 
> It is also the case that an inconsistent default graph makes the named graphs irrelevant.

"Irrelevant" is also not defined anywhere :-)

Pat

> 
> This last is, I think, a particularly strong point against providing this sort of semantics at all.
> 
> 
> peter
> 
> 

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Received on Thursday, 13 September 2012 03:11:42 GMT

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