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Re: Ill-typed vs. inconsistent?

From: Sandro Hawke <sandro@w3.org>
Date: Mon, 12 Nov 2012 10:20:47 -0500
Message-ID: <50A113CF.10506@w3.org>
To: Pat Hayes <phayes@ihmc.us>
CC: Richard Cyganiak <richard@cyganiak.de>, RDF Working Group WG <public-rdf-wg@w3.org>
On 11/12/2012 02:58 AM, Pat Hayes wrote:
> 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.

Pat, I think a lot of people should be using RDF who are not interested 
in the model theory.  It's a bit like people buys nails at the hardware 
store without knowing all the materials characteristics of the metal 
used.  (Whether they *can* understand the materials science is 
irrelevant, of course.)

      -- Sandro
>>  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 15:20:56 GMT

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