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Re: RDF-ISSUE-79 (undefined-datatype): What is the value of a literal whose datatype IRI is not a datatype? [RDF Concepts]

From: Dan Brickley <danbri@danbri.org>
Date: Wed, 9 Nov 2011 22:11:27 +0100
Message-ID: <CAFNgM+YhOc=koPULY-dUxnz92KxTqr76eUfa7MZu1DzYXNPkfA@mail.gmail.com>
To: RDF Working Group WG <public-rdf-wg@w3.org>
On 9 November 2011 21:53, RDF Working Group Issue Tracker
<sysbot+tracker@w3.org> wrote:
> RDF-ISSUE-79 (undefined-datatype): What is the value of a literal whose datatype IRI is not a datatype? [RDF Concepts]
>
> http://www.w3.org/2011/rdf-wg/track/issues/79
>
> Raised by: Richard Cyganiak
> On product: RDF Concepts
>
> The RDF Concepts spec (in both 2004 and 1.1 versions) does not answer the question what's the value of a literal where the datatype IRI doesn't actually denote a datatype, like <"foo",http://example.com/not-a-datatype>. This is surprising, as there is a section that normatively defines the value of *all other* literals.
>
> There are many possibilities:
>
> (i) the spec leaves it undefined
> (ii) that's not a valid RDF graph
> (iii) it's a valid RDF graph, but the value, if any, is unknown
> (iv) it's a valid RDF graph, and the literal is ill-typed
>
> This should be made explicit.
>
> The status quo is (i). I believe that the model theory says it's (iii).

-1 on (ii)
I don't like the notion that a single illformed triple could in some
sense "invalidate" a graph. There's a weaker sense in which the whole
graph, considered as a description, is no longer going to be a true
description in any interestingly relevant world. But "invalid" sounds
harsher than that.

Note that even mentioning such a construct with RDF'99's reification
vocabulary would (if (ii) were our rule) make the graph invalid. Which
probably just goes to show that reification still isn't quoting.

I'm ok with (i) (iii) or (iv). Whatever we do or say we'll have lots
of crap data and it'll get often get scrubbed somehow rather than
rejected absolutely. XML-style 'catch fire and burn' strictness
probably wouldn't serve us well here.

BTW how do we know a URI isn't a datatype? What about punning? e.g. it
might be a datatype proposal...

Dan
Received on Wednesday, 9 November 2011 21:12:05 GMT

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