W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > June 2002

Re: new semantics initiative

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Wed, 12 Jun 2002 10:52:11 +0300
To: Pat Hayes <phayes@ai.uwf.edu>, Brian McBride <bwm@hplb.hpl.hp.com>
CC: RDF Core <w3c-rdfcore-wg@w3.org>, Jonathan Borden <jonathan@openhealth.org>
Message-ID: <B92CD85B.168A2%patrick.stickler@nokia.com>

On 2002-06-12 7:23, "ext patrick hayes" <phayes@ai.uwf.edu> wrote:

> ...instead, we (ie the RDF coreWG) assume that the W3C will
> eventually have the good sense to declare that a certain namespace is
> *globally* understood to be 'rdf-invisible', in that any triples
> which use urirefs from that namespace are not asserted in any RDF
> graph.

Sorry to rain on the parade, but this is nonsense. Namespaces
are not significant nor represented in the RDF graph, and there
is no formal relationship between a URI and whatever namespace
prefix was used to hack it into the RDF/XML serialization.

Basing the designation of dark triples on namespace distinction
is impossible, since that distinction is an illusion.

C.f. http://lists.w3.org/Archives/Public/www-rdf-interest/2002Jun/0172.html

If you wish to simply say that the use of namespaces to trigger
an RDF parser to flag such statements as dark, well, fine, but
let's please be clear that it is a syntactic mechanism and not
a semantic one, and to that end, I can think of a number of
other possible (and IMO better) syntactic mechanisms for
indicating dark triples that are not based on namespace prefixes.

But saying "any triples which use urirefs from that namespace"
is nonsense since urirefs have no namespace. They are URIs,
not qnames, and they are fully opaque.

Presuming that triples have some indication of being dark
which is not based on namespaces, such as a simple bit,
then we're OK, and can proceed with dark triples and
the introduction of the proposed layering tweaks to the MT.

But there are *no* namespaces in the RDF graph. None whatsoever.

> (6) Does this require any changes to syntax/ test cases/ Ntriples/
> datatyping/ whatever?
> A: No.

I don't see how it would not. We would need a mechanism in RDF/XML
for setting the dark bit on statements and also an explicit
representation of that bit in NTriples (such as ';' rather than '.').

But that probably is not a great amount of work, and likely
could be done in a backward compatable manner.

[In case it's not clear, I'm pretty much in favor of providing for
 these layering tweaks to the MT and elsewhere, so long as they
 are not based on reference to namespaces]



Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Wednesday, 12 June 2002 03:48:08 UTC

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