- From: Graham Klyne <Graham.Klyne@Baltimore.com>
- Date: Mon, 23 Jul 2001 21:15:52 +0100
- To: Brian McBride <bwm@hplb.hpl.hp.com>
- Cc: Aaron Swartz <me@aaronsw.com>, w3c-rdfcore-wg@w3.org
At 11:44 AM 7/22/01 +0100, Brian McBride wrote:
>Aaron Swartz wrote:
>[...]
> > Today I came up with the idea that we could define anonymous
> > nodes as having a special representation in the abstract syntax,
> > but define the N-Triples conversion from RDF as having a
> > well-defined set of names for them. IOW, an algorithm such as
> > the one used by SiRPAC or CARA to generate anonymous nodes in
> > order could be specified somehow (using XSLT, for example), and
> > all RDF/XML parsers which outputted N-Triples could follow this
> > specification. That way, comparison of N-Triples documents could
> > be reduced to a simple sort/diff operation, while still
> > retaining the semantics of anonymous nodes.
> >
> > An example:
> > <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
> > <rdf:Description>
> > <rdf:value>foo</rdf:value>
> > </rdf:Description>
> > </rdf:RDF>
> >
> > could be unambiguously defined as:
> >
> > _:g0 rdf:value "foo" .
> >
> > as parsers would use anonymous node names in the form of _:gn
> > where n begins at zero and increments for each anonymous node
> > reached in the XML.
> >
> > Obviously this wouldn't work for N-Triples output from a data in
> > which ordering information had been lost (I have some ideas on
> > that one too, but they are less formed) but it would work for
> > any RDF/XML -> N-Triples conversion.
>
>Nice idea. Basically this would allow easy compare of models that
>came from the same RDF/XML serialization.
>
>One thing it wouldn't handle is the following example:
>
> <rdf:Description>
> <foo:bar>foobar</foo:bar>
> </rdf:Description>
> <rdf:Description>
> <bar:foo>barfoo</bar:foo>
> </rdf:Description>
>
>compared to:
>
> <rdf:Description>
> <bar:foo>barfoo</bar:foo>
> </rdf:Description>
> <rdf:Description>
> <foo:bar>foobar</foo:bar>
> </rdf:Description>
>
>These are representations of equivalent graphs which graph compare
>will find equivalent.
Brian,
I don't think it's a reasonable goal that a (simple) parser will generate
identical N-triples for equivalent graphs. I think it's enough that the
structures generated do not impede the design/application of an algorithm
to determine graph equivalence.
[...]
>If so, we are back into the complexities of graph theory.
I don't think we ever seriously got away from them if we want to evaluate
graph-equivalence.
#g
------------------------------------------------------------
Graham Klyne Baltimore Technologies
Strategic Research Content Security Group
<Graham.Klyne@Baltimore.com> <http://www.mimesweeper.com>
<http://www.baltimore.com>
------------------------------------------------------------
Received on Monday, 23 July 2001 18:06:02 UTC