Re: [xtm-wg] A challenge on "the graph"

[Murray Altheim <altheim@eng.sun.com>]

Bernard Vatant wrote:
[...]
> What can I can say NOW is, out of an afternoon on the phone with the graph
> people (BTW not "professeurs" but "chercheurs")
> 
> The model they propose is ridiculously simple. Just a translation of nodes
> and arcs into ... vertices and edges :)
> They say indeed : Topic Maps are so simple. Why did you complicate them with
> all that unnecessary twisted syntax ?

Because topic maps are not an implementation of graph theory, as can be 
claimed (as has been) of RDF. The "unnecessary twisted syntax" expresses IMO
very well the *specific* semantics of the various relationships in a topic
map document, with all its nooks and crannies. We could have created a more
generalized syntax like RDF, where everything was "in a namespace" and the
syntax itself provided only the rudiments of tuples. RDF is a general purpose
tool, XTM is a tool to represent, well, topic maps. It just so happens that
the word chosen to represent a topic map "in memory" is "graph," and it is
demonstrably possible to represent a topic map as a graph. But a topic map
is not *simply* a graph, and for purposes of interchange we wanted to make
explicit in syntax the various topic map features.

While syntax has a lot to do with markup style, I for one have little 
difficulty in creating or "reading" XTM syntax, while most RDF requires at
least two or three cups of coffee to comprehend, especially when one isn't
using a well-known flavour like Dublin Core.

> The nodes of the same type have the same color. So have the arcs of the same
> type. Some TM elements will be nodes, some other will be arcs. There will be
> basic rules on the colors of nodes and arcs, and that's all there will be
> ... In fact, it's as simple and obvious as Topic Maps looked to me ...
> before I began to look into the syntax :o)
> 
> And they claim : " The graph modeling shows some inconstencies and
> shortcomings of the XTM syntax model and the DTD. But it's very easy to
> clean that". And I said : *Please* - there has been enough of blood and
> tears - don't *ever* mention the DTD.

While I'm not interested in making any changes to the XTM DTD, as this
would seriously damage further development of XTM (and I'd definitely
begin looking for other work), I'd be still interested in understanding
their issues. If you don't want to start a bloodbath online, send this
to me privately.

> BUT ... they know how to put these sets of colored nodes and arcs in a
> system and have algorithms to spider the graph and query and retrieve
> amazing things you just can't do in a relational data base, like : "Take any
> (A,B) in a set of entangled genealogical trees. Find every couple made of a
> descendant of A married to a descendant of B". Or : "Find me a family where
> all members of three following generations were born, married and dead in
> the same county". Weird things like that. And they claim these algorithms
> have been around for ages.

If they're open source, let me at them. This is precisely what Sam, I and 
others have been asking about.

> And they claim it's not academic work, and that Francfort's Airport traffic
> and New York's garbage collection, among others, are working with
> implemented models grounded in graph theory. And they've brought some
> interesting features into Mondeca software, too, as some of you know ...
> 
> So we have at hand a conceptual model and a processing model, and query
> algorithms, all grounded in the most universal representation language I
> know, and I think less controversial than any of those passing by lately :
> mathematics ...
> 
> What more ? We'll have a F2F meeting next week to put all that down in a
> single document for the community use.
> I propose to write down that document in such a way that it meets the
> mathematicians' requirements and the eagerness of XTM community to
> understand them.

Well, I for one definitely look forward to seeing this document.

Murray

...........................................................................
Murray Altheim                            <mailto:altheim&#x40;eng.sun.com>
XML Technology Center
Sun Microsystems, Inc., MS MPK17-102, 1601 Willow Rd., Menlo Park, CA 94025

      In the evening
      The rice leaves in the garden
      Rustle in the autumn wind
      That blows through my reed hut.  -- Minamoto no Tsunenobu

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