The most distinctive features of the Topic Maps
paradigm have to do with reification:
Reification
- Subjects can "appear" in property values, without being reified. (There must always be some of these; topic maps must be finite.)
- Note: If the Topic Map Application (read: governing
ontology) permits it, the same subject can make both reified and
unreified appearances in a topic map. Obviously, only the
reified appearances can be merged.
- In Topic Maps, to reify or not to reify is an ontological
commitment.
- Nobody is licensed to understand a topic map as having
reified a subject that it does not actually reify. (This
contrasts sharply with at least some doctrines for the use of
RDF.)
- A subject can only be reified if the ontology defines a Subject
Identity Property that can have a value that can identify the
subject.
