[topicmapmail] graphic language for describing TopicMaps

[Murray Altheim]

Thomas Schwotzer wrote:
[...]
> I have doubts that RDF visualization can easily be applied to
> Topic Maps. The RDF triples can be visualized as graphs.
> That's straightforward.
> 
> In Topic Maps, associations define relations between an arbitrary
> number of topics. TMs are hypergraphs.

Thomas,

My understanding of hypergraphs (as defined e.g., by W.T. Tuttle
in "Graph Theory" and elsewhere) is that it is a graph containing
a graph. This is assuming that hypergraphs and subgraphs are
essentially the same thing viewed from opposite sides of a mirror.

I don't see that the number of topics in an association would
constitute a hypergraph. It can still be considered as one, flat
graph structure. There are certainly specific ontological constructs
where a hypergraph visualization might provide an improved match
between the representation and the constructs being represented,
and the idea of being able to collapse a portion of a visualized
graph can be quite valuable.

But on the whole, while RDF and TM have decidedly different graph
structures, both seem to have a flat graph, not a hypergraph, as
their basic structure. Since Topic Maps can't actually contain
other Topic Maps, except by reference, this would seem to be the
case.

Is there something I'm missing?

Murray

......................................................................
Murray Altheim                    http://kmi.open.ac.uk/people/murray/
Knowledge Media Institute
The Open University, Milton Keynes, Bucks, MK7 6AA, UK               .

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