[topicmapmail] Questions About XTM Occurrence Semantics

[Lars Marius Garshol]

* Peter P. Jones
>
> [what reifying occurrences means]
>
> Ah, do you mean here that the reifying topic would carry the same  
> IRI for its subject identifier as the occurrence value?

No. When you attach an occurrence to a topic A with a URI B there are  
three subjects involved:

  (1) the one represented by A,
  (2) the one referred to by B, and
  (3) the relationship between the two.

The occurrence represents (3) (as you can see from

   http://www.isotopicmaps.org/sam/sam-model/#sect-occurrence

), and so the reifying topic also represents (3).

> If so, that's not quite what I'm after. I'm after having the  
> reifying topic refer to the occurrence in the TM as a _particular_  
> occurrence, yet also indicate that there is a distinction between  
> auditing the insertion of an occurrence into the map and, as one  
> way of putting it, dereferencing via the occurrence.
> The occurrence should be the subject identifier of the reifying  
> topic, and not the IRI, yet it matters (to me pushing this little  
> envelope about) that somehow the intent that the IRI of the  
> occurrence is the target rather than the ID of the occurrence  
> element is important.
> Another way of saying it is that I would like to be able to refer  
> to the unique usage of the subject identifying IRI in a particular  
> position within the TM, that particular occurrence, so that the  
> reifying topic doesn't just identify (or merge) on the basis of  
> where the subject identifier IRI address indicates.
> Is that pushing things too far?

I'm sorry, but I didn't really understand any of this. Maybe I can  
clarify some things, though:

  - There is no subject identifier here. Yes, XTM 1.0 uses the
    <subjectIndicatorRef> element to refer to the occurrence to
    be reified, but in the model this actually turns into a topic
    that refers directly to the occurrence, and the URI itself
    disappears.

  - "IRI of the occurrence" is ambiguous. Does it mean the IRI of the
    resource that is an occurrence, or of the <occurrence> element?

The easiest way to deal with this is probably if you explain this:  
what is your subject? What is it you want to create a topic to  
represent?

-- 
Lars Marius Garshol                         Mobile: +47 98 21 55 50
CTO, Ontopia                                Office: +47 23 23 30 83