[topicmapmail] Questions About XTM Occurrence Semantics

[Peter P. Jones]

Lars Marius Garshol wrote:
> Hi Peter,
> 
> * Peter P. Jones
>>
>> Imagine I have a topic for some subject and in some scope, say {a,b,c},
>> that topic has an occurrence with a particular locator.
>>
>> If I reify that occurrence, what is the precise meaning of the reifying
>> topic construct?
>>
>> Is it:
>> a) A reification of the particular information item that is that
>> occurrence? So I can talk about the information item.
>> b) A reification of the particular occurrence of the subject somewhere
>> (outside TM-land)?
>> c) Something else I haven't thought of.
> 
> The answer is b). XTM 1.0 is silent on this (as far as I can remember), 
> but TMDM is (IMHO) pretty clear on this:
> 
>   http://www.isotopicmaps.org/sam/sam-model/#d0e994
> 
>> What I would like is to reify a particular occurrence, but I would also
>> like the intent of the reification to be that I am reifying the
>> occurrence of the subject and not the technical construct of the TM
>> information item, if that is possible.
> 
> That's the standard semantics, so no worries.

Ah, do you mean here that the reifying topic would carry the same IRI 
for its subject identifier as the occurrence value?
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?


> 
>> In the reifying topic construct, does it make a difference w.r.t. the
>> above whether I use a subject locator or subject identifier.
>> I.e. does subject locator provide for (b) while subject identifier
>> provides for (a)?
>> Or are matters more like (c)?
> 
> If you use a subject locator in the syntax the standard says nothing 
> about what it might mean beyond the general semantics of the subject 
> locator constructor. I would take that to mean that using a subject 
> locator means you are talking about the XML element in the XTM file.
> 
> I hope this helps.

Yes, thanks.

--
Peter

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