Re: [topicmaps-comment] RE: Ontological extravagance in the Topic MapGraph?

[Sam Hunting <sam_hunting@yahoo.com>]

Ivan--

It's great to see RDF topic map convergence advocated as a goal -- we
don't hear that often enough on this list.

If by ontology we understand "a set of concepts  ... that are specified
in some way (such as specific natural language) in order to create an
agreed-upon vocabulary for exchanging information", I see the same
number of *concepts* in each proposal -- the same set of concepts
mappped to a different set of graph construction rules. So, assuming
that the number of concepts is the right metric to measure extravagance
in an ontology, each proposal is extravagant in equal measure. (I'm not
all that certain that 4 arcs and 3 nodes are all that extravagant.)

I'm not sure how to evaluate an ontology for "fitness of purpose"
(which I think is the phrase Ann Wrightson would use). For example, I'm
not sure if a statement like "this type of node makes this type of
function easier to implement" is appropriate for ontology evaluation.
Perhaps ontologies have their own inner design integrity ("smell", in
extreme programming terms), regardless of what is done with them?

This is cross-posted to the general topic map list, in case it is felt
that this is not appropriate to an OASIS list.

S.








--- Ivan Uemlianin <ivan@jurakm.com> wrote:
> Why are so many different types of nodes, arcs, non-node and non-arc
> objects
> needed in the topic map graph?
> 
> According to tmpm4, the topic map graph has the following entities: 
> three
> types of node (topic, association and scope) and four types of arc
> (association-member, association-scope, association-template and
> scope-component).  There are also the non-node subject identity
> points and
> the non-arc links between topic nodes and subject identity points,
> both of
> which are outside of the graph, but are nonetheless part of the
> ontology
> defined by tmpm4.
> 
> It is possible to represent the same set of graphs with a smaller
> ontology,
> specifically: three types of node (topic, association and literal)
> and one
> type of arc (association-member).  Association-scope and
> association-template arcs are here represented by association-member
> arcs,
> labelled (i.e. with 'role' specified) as 'scope' and 'template'
> respectively.  Subject identity points are represented as literal
> nodes
> (with resource being a special case of literal), and topic nodes are
> linked
> to these literal nodes via association-member arcs.
> 
> Presumably there were reasons to introduce the reified nodes and arcs
> (i.e.
> scope nodes, and association-scope, association-template and
> scope-component
> arcs) and to create ill-defined non-graph appendages (i.e. the
> subject
> identity points and the links to them).  However, not only do they
> complicate a simple ontology, they increase the distance between
> graphical
> representation of topic maps and RDF.  Simple graph ontology and
> simple
> RDF-TM links both seem like reasonably good ideas.
> 
> So, why such a complicated ontology?
> 
> Ivan
> 
> Ivan Uemlianin, PhD
> 
> Head of Topic Map Development
> Jura Technology Limited
> 
> 6 Tai Seion
> Llanddeiniolen
> Caernarfon
> Gwynedd LL55 3AF
> Wales, UK
> 
> Head Office:
> 35 Norroy Road
> Putney
> London SW15 1PQ
> UK
> 
> 
> 
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