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RE: Trust, Context, Justification and Quintuples

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Fri, 19 Dec 2003 13:31:13 +0100
To: "Graham Klyne" <GK@ninebynine.org>, "Chris Bizer" <chris@bizer.de>, <www-rdf-interest@w3.org>

I note that contextID behaves very different semantically from the

I suggest that instead of a quadruples or quintuples approach that this
difference in semantics is better reflected by naming graphs (sets of

In work I am doing with Patrick Stickler we present contexts as a map from
nodes to graphs, where the nodes (uriref or blank) act as the name of the
graph. This explicitly is a quoting mechanism, and is trivially
transformable into quads but with clearer differences in semantic intent.

For many trust applications (e.g. digital signature) I need to have locally
complete knowledge. If I have quads

ID, a, b, c
ID, a1, b1, c1
ID, a2, b2, c2

whose to say that there is not another quad somewhere

ID, a3, b3, c3.

But if I have a map including

ID => { < a, b, c >
        < a1, b1, c1 >
        < a2, b2, c2 > }

then it is clear that ID is not related to <a3 b3 c3>.

Also we can avoid the problems with reification not being a quoting
mechanism since this graph naming explicitly *is* a quoting mechanism (up to
graph equivalence, as defined in RDF Concepts).


> -----Original Message-----
> From: www-rdf-interest-request@w3.org
> [mailto:www-rdf-interest-request@w3.org]On Behalf Of Graham Klyne
> Sent: 18 December 2003 22:47
> To: Chris Bizer; www-rdf-interest@w3.org
> Subject: Re: Trust, Context, Justification and Quintuples
> It has been a while, but when I thought about this I came to the
> conclusion
> that just one of (context-id) or (stating-id) was sufficient.
> E.g. given a (stating-id), (contexts) can be created as RDF
> containers and
> their contents can be the required collection of (stating-id).
> Or, if (context-id) is used, then statements or groups of
> statements can be
> isolated and referenced by placing them into separate (contexts).
> #g
> --
> At 15:05 18/12/03 +0100, Chris Bizer wrote:
> >Hi everybody,
> >
> >we did some brainstorming about trust, context and the justification of
> >query results and ended up with:
> >- an extended RDF data model based on quintuples (a triple plus two
> >additional elements: context and statement ID).
> >- a trust-oriented query language for this data model
> >- the concept of justification trees for tracking data
> provenance and data
> >lineage.
> >
> >See: http://www.wiwiss.fu-berlin.de/suhl/bizer/trustcontextjustification/
> >
> >Our approach is much more data-oriented than the proof-oriented work of
> >McGuinness and da Silva published at ISWC 2003 [1]. But we think
> for SemWeb
> >applications which don't do heavy inferenceing such a approach could be
> >sufficient.
> >
> >Is somebody working on similar approaches?
> >Do you know any other groups working on the topic?
> >
> >What do you think about extending the RDF model for capturing context?
> >What do you think about the approach in general?
> >
> >We are looking forward to any feedback :-)
> >
> >Regards
> >
> >Chris Bizer
> >
> >http://www.wiwiss.fu-berlin.de/suhl/ueber_uns/team/chris_bizer.htm
> >
> >[1]
> >http://www.cs.toronto.edu/semanticweb/resource/reference/iswc03be

Graham Klyne
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Received on Friday, 19 December 2003 07:31:32 UTC

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