[topicmapmail] XTM-RDF conversion

[Dicheva, Darina]

Hello all,

We are currently implementing an XTM-RDF conversion for TM4L. In this
relation, I would like to ask for an opinion on translating  TM
associations.  The requirements "convert with no/acceptable loss of
information" and "translate the association close to the way RDF users
would express Topic map associations" are somewhat contradictory.  The
problem  is that RDF is built on directional binary relations:
Subject-Property-Object, while in TM a binary association  authorship
has five elements:

authorship(author: Shakespeare, work: Hamlet).

Using scopes, we can define different names of the relationship type for
both directions:

wrote (scope=Author) & written-by (scope=Work).
 
Currently we are thinking of translating such an association as

	Author -- wrote -- Work

but are wondering whether to include also the reverse part of the
relationship in the translation:  

	Work -- written-by -- Author  

How would including it, or not including it, affect RDF
completeness/readability/inference capability?  Clearly, if we want to
represent both directions, we'd have to make two statements per every
association instance: 
 
	Shakespeare -- wrote -- Hamlet &
	Hamlet -- written-by -- Shakespeare
 
Would that be undesirable?

There are, of course, other more thorny issues related to scope and
variants, but piece-by-piece.
 
I would much appreciate any feedback on translating TM association into
RDF statements. 
 
Thanks,
Darina