[sc34wg3] Reification or Representation?

Martin Bryan sc34wg3@isotopicmaps.org
Sun, 22 Aug 2004 17:55:53 +0100

Coming back from holiday in a befuddled state (after a wet fortnight in
Ireland, what do you expect?) I have read through the debate on Reification
or Representation with bemusement - its all far too abstract for me :-)

As far as I can work out, Lars et al, in TMDM, restrict the meaning of the
term reification to refer to the set of topics whose point of reference is a
"Topic Map Construct" - some component of a topic map tree, represented in
some concrete computing language. It would seem likely, though this point is
not perfectly clear to me, that Lars et al believe that what such reified
topics have as their subject is not some part of the topic map tree itself,
but the nodes "identified" by that particular subset of the topic map tree.
[My confusion with this is that I still don't see how I can make the subject
of my topic the fact that an association has been set up between something
with this role and something with that role ... but hopefully someone will
explain that in terms I can comprehend one day.]

Steve Newcombe, on the other hand, seems to use reificiation in a much wider
sense, whereby any topic defined within a topic map tree is a physical
representation of some abstract concept. This can be thought of as the
"classical view" of the term.

It seems to me that the two uses of the term are not different, but that one
is more restricted than the other in that it introduces a specific
constraint that the subject being reified has already been recorded as a
node in a topic map tree.

Interestingly, the New Oxford Dictionary of English offers an alternative
definition of the term reify - which might give us a small clue as to how we
might make better use of the term: "make (something abstract) more concrete
or real".

The point that seems to have been missed is that a topic map is a physical
(e.g. concrete) representation (if only in terms of bits) of an abstract
concept. There can be many different physical representations of a given set
of abstract concepts, depending on which language (HyTM, XTM, LTM, RDF, ...)
is being used to represent it. We should be careful not to bias ourselves by
using terms that are specific to a given language.

(As an aside, I have returned from Ireland inside a cat, but not the one
advertised in Dublin as the Seacat. We passed the Isle of Man, which reminds
me that not all cats share common characteristics, such as tails. And when
we refer to big cats we don't generally include sea-going cats in the same
category. The point of this diatribe is to remind everyone that words mean
what the context they are used in determine they mean, not something
concrete - they are very impure abstractions for a concept.)

Is there a solution to the fundamental dichotomy between the use of the term
reificiation in ISO 13250 and TMDM? Is the fundamental difference in the use
of the term that TMDM is trying to introduce a new concept something along
the lines of "the purpose of reification within TMDM is to make concrete an
abstract concept that has been introduced by relationships between the
components of a particular topic map tree"? Am I right is suspecting that
what is being reified within TMDM is, for example, the fact that a
particular association has a given set of roles that are undertaken by a
given set of subjects that have been represented by a particular set of
topics? In other words, is it the tree subtended from the node being
referenced that is important, rather than the node itself, or the sum of the
concepts identified by the nodes?

Confused of Churchdown