# [sc34wg3] Representing ordered sets in Topic Maps

**Dmitry
**
sc34wg3@isotopicmaps.org

*Mon, 27 Oct 2003 21:19:08 -0500*

I would like to suggest topic for discussion: representing ordered sets
using Topic Maps.
For example, it is easy to represent information that a person is an author
of some book. It is easy to represent information that some people are
coauthors of some book.
But I am not aware of standard easy way to represent information that
coauthors should follow specific order.
I saw several approaches to this problem:
- rely on order of members in XTM document (well, simple but ... invalid)
- introduce set of roles such as 'author_1', 'author_2' etc.
- introduce additional role 'position' in 'coauthor' association with values
such as http://<some location>/numbers#1, http://<some location>/numbers#2
- introduce explicit topics for groups, create types of ordered groups and
association "ordered member"
- implement 'list' data structure using set of topics and associations
(head,tail roles)
I think it is important to define "standard" way to represent ordered sets
in XTM/TMDM and probably TMQL/TMCL require some specific operations to work
with ordered sets.
Dmitry