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RE: Comments on the new RDF Test Cases draft

From: Jan Grant <Jan.Grant@bristol.ac.uk>
Date: Fri, 31 May 2002 10:35:12 +0100 (BST)
To: Brian McBride <bwm@hplb.hpl.hp.com>
cc: Massimo Marchiori <massimo@w3.org>, phayes <phayes@ai.uwf.edu>, www-rdf-comments <www-rdf-comments@w3.org>
Message-ID: <Pine.GSO.4.44.0205311028250.29324-100000@mail.ilrt.bris.ac.uk>

On Fri, 31 May 2002, Jan Grant wrote:

[I've lost the attributions, sorry]

> > >Therefore, such "word smoothering", plus a precise definition of
> > >isomorphism, suffice. But, note that if we go along the
> > >"smoothering way", the same problem of a precise definition of
> > >isomorphism can be nicely dropped as well, as the wording can well
> > >say that the "expected output" is the given N-triple one, and just
> > >be silent on the isomorphism issues at all (as, it's rather clear
> > >that N-triple output is defined modulo renaming of blank nodes, and
> > >in any case, crucially, no *formal* definition is then needed as
> > >the Test Cases contain clarification guidelines, and not formal
> > >normative definition of "test passing for parsers").

Ack! I didn't notice this before!

I should say that jeremy Carroll is producing a document describing what
we mean by "an RDF graph" including an expression of the appropriate
notion of isomorphism.

But I see you're talking about "renaming blank nodes". Blank nodes
_don't_ have names. They have identity wrt the graph they're a part of;
the "names" are simply an artifact of the serialisation syntax and have
no non-local meaning.

An N-Triples document is just a description of an RDF graph, which may
contain some blank nodes; they really are (honest!) blank.

jan

PS. I'm still somewhat surprised by complaints about abusing
graph-theoretic terms. Like I said before, the graph theorists I've met
all seem to play fast and loose with terminology (where context is
obvious) and have few qualms about dealing with graphs, multigraphs,
partially-labelled multi-digraphs, etc. and will still tend to refer to
them all as a "graph" when talking.

-- 
jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/
Tel +44(0)117 9287088 Fax +44 (0)117 9287112 RFC822 jan.grant@bris.ac.uk
I am now available for general use under a modified BSD licence.
Received on Friday, 31 May 2002 05:38:32 GMT

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