W3C home > Mailing lists > Public > www-rdf-interest@w3.org > June 2002

Re: Implementing statement grouping, contexts, quads and scopes

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Tue, 25 Jun 2002 10:27:58 +0300
To: <areggiori@webweaving.org>, Jonathan Borden <jonathan@openhealth.org>
CC: RDF Interest <www-rdf-interest@w3.org>, RDF Logic <www-rdf-logic@w3.org>
Message-ID: <B93DF62E.174FC%patrick.stickler@nokia.com>

On 2002-06-24 20:48, "ext Alberto Reggiori" <areggiori@webweaving.org>

> Jonathan Borden wrote:
>> Don't you see what you are trying to do?
> I think I can see what I am trying to do here, which is proposing a practical
> solution (like Patrick I guess) to layer new semantics on top of RDF using
> reification and the current XML/RDF syntax which most parsers understand
> already :-)
> Isn't the WebOnt supposed to layer OWL on top of RDF  using the XML/RDF _as it
> is today_  [1] or am I missing something here ? :-)

Well, the RDF Core WG *could* change RDF to accomodate the layering
needs of OWL, since it appears to be a critical need that will have
long range impact on the development of the SW.

I was simply trying to point out that RDF *already* provides for dark
(unasserted) triples, even if folks don't consider the syntax to be
their cup of tea, and that it makes far more sense to consider
making the syntax more palatable without extending the core RDF
machinery or introducing a second way to express unasserted triples.

An OWL-specific RDF API could make the statements which are unnasserted
at the RDF layer appear asserted at the OWL layer, allowing RDF
and OWL applications to operate off the very same triples store.
Likewise for any other layer above OWL. It's simply a matter of
perspective then, which statements are asserted or not, and that
perspective is different at each layer. But the underlying RDF model
can be used for all layers.

So, arguments against such a proposal based on the obesity of
the syntax are very easily addressed by introducing the contracted
form I proposed (and since parsers anyway will have to be updated
to support other changes to RDF/XML, such as parseType="Collection",
this is not at all an unreasonable thing to ask). And arguments
that unasserted OWL statements will have a different graph
representation from asserted RDF statements can be addressed by
OWL specific APIs as described above such that generic inference
engines interfacing with the OWL level API will "see" unasserted
RDF statements with OWL vocabulary as asserted RDF triples.

Thus, such an approach lets both RDF and OWL have their cake
and eat it too, without either having to eat the other's cake.


Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Tuesday, 25 June 2002 03:23:35 UTC

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