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Re: RDF-ISSUE-109 (ill-typed-so-what): What's the consequence of a literal being ill-typed? [RDF Concepts]

From: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>
Date: Sun, 11 Nov 2012 11:59:40 +0100
Message-ID: <CA+OuRR8X=MOKG+i1GJa=pGN2EeH6co1XZ=QXL0TQS7EnriE97w@mail.gmail.com>
To: RDF Working Group <public-rdf-wg@w3.org>
I'm affraid this distinction between "inconsistent graph" and "graph
containing ill-formed literals" is inevitable, in general.
The problem is that you can not expect all RDF-consumming agents to know
about all possible datatypes.
Consider:

  @prefix : <http://example.org/ns/>
  :foo :prop "bar"^^:custom-datatype .

If RDF-consistency depended on the well-formed-ness of the literal,
then a general-purpose RDF processor could simply not decide whether the
above graph is consistent or not.
This would be embarassing...

That being said, recommending that all RDF processors MUST or SHOULD
understand the semantics of the datatypes listed in the abstract syntax
documents would certainly sound like a good idea, IMHO.

  pa


On Fri, Nov 9, 2012 at 10:11 AM, RDF Working Group Issue Tracker <
sysbot+tracker@w3.org> wrote:

> RDF-ISSUE-109 (ill-typed-so-what): What's the consequence of a literal
> being ill-typed? [RDF Concepts]
>
> http://www.w3.org/2011/rdf-wg/track/issues/109
>
> Raised by: Richard Cyganiak
> On product: RDF Concepts
>
> (Raising and issue on this for referencing in the upcoming new Concepts WD)
>
> What's the relevance of the distinction between “graphs containing
> ill-typed literals” and “inconsistent graphs” in the Semantics?
>
> The text stresses that the presence of an ill-typed literals does not
> constitute an inconsistency. But why does the distinction matter? Is there
> any reason anybody needs to know about this distinction who isn't
> interested in the arcana of the model theory?
>
> >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.
>
> What should an implementation do? Should authors avoid generating such
> graphs? Should consumers reject it? Is an implementation that rejects
> ill-formed xsd:dates conforming?
>
>
>
>
Received on Sunday, 11 November 2012 11:00:08 GMT

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