Re: Issues danc-01 Re: 2 formalities in RDF concepts

On Wed, 29 Jan 2003, Dan Connolly wrote:

>
> On Wed, 2003-01-29 at 03:41, Jan Grant wrote:
> > On Tue, 28 Jan 2003, Dan Connolly wrote:
> >
> > > > Jeremy's talking about *syntactic* equality (ie, "X equals Y" means
> > > > "every expression involving X can be rewritten with Y substituted for it
> > > > and the expression's value is preserved"),
> > >
> > > Hmm... I wasn't familiar with that idea before... I'll have
> > > to think it over.
> > >
> > > But my intuition says the difference between syntactic
> > > equality and identity matters to the RDF spec.
> > >
> > > For example, if X and Y are distinct graphs that
> > > art syntactically equal, what's the cardinality
> > > of the set {X, Y}? It's 2, right?
> > >
> > > The model theory spec does stuff like putting
> > > graphs into sets, and I think it matters what
> > > the cardinality of the resulting set is;
> > > if X and Y are the graphs arising from
> > > the n-triples document jeremy gave as
> > > an example, I think the model theory
> > > spec depends on the cardinality of {X, Y} being 1.
> > >
> > > But I'm not certain. It could be that it doesn't
> > > matter.
> >
> > It doesn't; it's akin to thinking about how many number 10s there are:
> > you can take a view, but it's irrelevant to the way you do arithmetic.
>
> You're 100% certain that the RDF semantics document
> is indifferent to the cardinality of {X, Y} above?
> I'm not (yet) convinced.

Yes, absolutely.

-- 
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/
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