[topicmapmail] LTM 1.3 Change Proposal

[Lars Marius Garshol]

* Jan Algermissen
| 
| would maybe be a good idea to look for principles that a decision
| could be based on/evaluated against.

Yes, it might be. XTM 1.0 has a set of requirements at the top, but
they don't really help much, and personally (ie: with 4 years of
hindsight) I think they were too limited.

| The issue you are dealing with here is the one of 'missing
| information', well known in the data management scene. Also closely
| related to SQL's null values and the evils of the resulting three
| valued logic in SQL (true, false, and null). Duhhhh....

Well, topic maps and RDBMSs are different here. We are both vulnerable
to the tree-valued logic horror, but RDBMSs have to have NULLs because
of the tight connection between logical storage and the schema. That
is, if PERSON has a DATE_OF_BIRTH column, every person must have a
value there. This doesn't apply to topic maps, where the author can
decide whether or not to create a date-of-birth occurrence. 

And, in fact, for topic maps the problem Murray and I are discussing
is much worse, because it amounts to having NULL columns (and tables)
where a NULL column on row X may be different from the NULL column on
row Y.

This is quite a complication, and I don't see that the complication
buys us anything at all, as I argued in my email to Murray.

-- 
Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >