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Re: Trust, Context, Justification and Quintuples

From: Chris Bizer <chris@bizer.de>
Date: Fri, 19 Dec 2003 14:27:45 +0100
Message-ID: <00fb01c3c633$e32bb4f0$0f8d2da0@wrz03295>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>, "Graham Klyne" <GK@ninebynine.org>, <www-rdf-interest@w3.org>

Hi Jeremy,

> I note that contextID behaves very different semantically from the
> subject/predicate/object.
>
For my better understanding, can you explain this in more datail or give me
a link?
The idea of cRDF as logic model on top of RDF is, that a specific context is
a instance of the class cRDF:context and you can make statings about this
instance. I don't see why this is semantically out of the scope of RDF?

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

Is there something written with more details about this maps?
If I'm getting the approach right, you say you are using all nodes together
as name of the graph?
And this name is used afterwards to refer to the graph? Or has the graph
another ID and the map is something like a container expressing which nodes
belong to the graph? My first interpretation sound very inefficient from the
implementation point of view.

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

Isn't having locally complete knowledge impossible by definition in the
Semantic Web?

> 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>.
>
Do I assert

<ID, dc:date, 2003-10-10>

or

<{ < a, b, c >
  < a1, b1, c1 >
 < a2, b2, c2 > } dc:date, 2003-10-10>

?

Sorry if I got you totally wrong :-)

Chris

> 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).
>
> Jeremy
>
>
>
> > -----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
> stpapers/iswc03-infrastructure-web-explanations.pdf
>
> ------------
> Graham Klyne
> For email:
> http://www.ninebynine.org/#Contact
>
>
>
>
Received on Friday, 19 December 2003 08:25:52 GMT

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