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Re: Ill-typed vs. inconsistent?

From: Pat Hayes <phayes@ihmc.us>
Date: Mon, 12 Nov 2012 01:58:51 -0600
Cc: RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <51FE010C-46E9-48ED-B40D-8F3B7AA6220A@ihmc.us>
To: Richard Cyganiak <richard@cyganiak.de>

On Nov 8, 2012, at 1:13 PM, Richard Cyganiak wrote:

> What's the relevance of the distinction between “graphs containing ill-typed literals” and “inconsistent graphs” in the Semantics?

The relevance is that it is quite possible to say sensible (and therefore consistent) things about ill-typed literals, such as that they are ill-typed. 

> 
> The text stresses that the presence of an ill-typed literals does not constitute an inconsistency.
> 
> But why does the distinction matter?

I am not sure what you mean by "the distinction" here. Why would you expect that an ill-typed literal would produce an inconsistency? Why would the presence of an ill-typed literal make a triple false?

> Is there any reason anybody needs to know about this distinction who isn't interested in the arcana of the model theory?

I'm not sure what you consider to be "arcana". Someone who cannot follow the model theory probably shouldn't be using RDF.

> 
> From the perspective of someone who authors RDF data, or works with RDF data, they both seem like belonging to the same class of problem, and I'm a bit at a loss as to how to explain the difference.

To me they seem quite obviously different, so apparently I am not following your intuition here. FWIW, one should *not* think of inconsistency as a kind of error condition. (Maybe the semantics text should spend a little time explaining this point.)

> 
> (I know how both terms are defined and what conditions exactly cause them; the question is about why the spec insists that ill-typed literals do not cause a graph to be inconsistent.)

My question, in reply, would be to ask why anyone would think it would.

Pat

> 
> Best,
> Richard
> 

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Received on Monday, 12 November 2012 07:59:22 GMT

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