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Re: 2 formalities in RDF concepts

From: Jan Grant <Jan.Grant@bristol.ac.uk>
Date: Tue, 28 Jan 2003 11:25:49 +0000 (GMT)
To: Dan Connolly <connolly@w3.org>
cc: RDFCore Working Group <w3c-rdfcore-wg@w3.org>
Message-ID: <Pine.GSO.4.44.0301281114040.13893-100000@mail.ilrt.bris.ac.uk>

On Mon, 27 Jan 2003, Dan Connolly wrote:

>
> re http://www.w3.org/TR/2003/WD-rdf-concepts-20030123/
>
> I'm going over it with a fairly fine-tooth comb,
> updating my larch stuff.
>   http://www.w3.org/XML/9711theory/RDFAbSyn.lsl
>
> I found 2 bugs:
>
>     % 6.3 Graph Equality
>     % REVIEW: if this is really equality/identity
>     % (and I think the model theory sees it as such)
>     % then a graph isn't just a set of triples;
>     % it's an equivalence class of sets of triples
>
> if a graph is a set of triples, then graphs are
> equal when they contain the same triples, full stop.
> Not so. Pls fix.

Jeremy's terminology (using "equal" for syntactic equality) seems to rub
pretty much everyone up the wrong way, although it is technically
correct. A move to using "graph isomorphism" is pure syntactic sugar,
although I'll note that this terminological fix will also require a fix
to a couple of words in the test cases document: Massimo objected to
using "isomorphic" to describe the, erm, isomorphism relation between
graphs, which is why test cases now points to jjc's definition...

[[
A parser is considered to pass the test if it produces a graph  equal to
the graph described by the N-triples output document, according to  the
definition of graph equality given in [RDF-CONCEPTS].
]]


> 2ndly...
>
> specification of literals is goofy... "A literal in an RDF graph
>   contains three components called: ...
>   The datatype URI being an RDF URI reference. ...
>   A plain literal is one in which the datatype URI is absent."
> Hello? you just told me every literal has one.
>
> Specify that the datatype URI and language identifier
> are optional.

Agreed; possible different interpretations of this make it hard to
answer GK's question: can the literal "a" denote the same thing as the
typed literal "a"^^xsd:string. I'd support clarifying this wording so
that any remaining ambiguity is solely on the XSD side.


-- 
jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/
Tel +44(0)117 9287088 Fax +44 (0)117 9287112 http://ioctl.org/jan/
I'm the dandy information superhighwayman.
Received on Tuesday, 28 January 2003 06:26:32 EST

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