RE: [topicmaps-comment] occurences and modeling resources

[Howard Goldberg <HGoldberg@cstlink.com>]

> -----Original Message-----
> From: Lars Marius Garshol [mailto:larsga@garshol.priv.no]
> Sent: Tuesday, December 18, 2001 1:54 PM
> To: topicmaps-comment@lists.oasis-open.org
> Subject: Re: [topicmaps-comment] occurences and modeling resources
> 
> 
> 
> * Howard Goldberg
> |
> | 1.  In the conceptual model, an occurence is uniquely identified by
> | an instanceOf, a scope, and a resourceRef.  Therefore, it appears
> | that any occurrence that shares the same tuple should have the same
> | occurence identifier.  
> 
> If two occurrences of the same topic have the same values for these
> properties (as well as for the <resourceData>, if they have any) they
> need to be replaced by a single occurrence. (XTM 1.0, annex F.2.6.) 
> I am not sure if this is what you are thinking of, however.
> 
> This is not the same as saying that the identity of an occurrence
> object in the internals of a topic map engine is necessarily
> determined by these four values. There is no rigorous specification of
> what is required here, nor do I think that there should be.
> 
> What you mean by "occurrence identifier" I don't know. Could you
> explain? Your question seems to be about this identifier, so it sounds
> important. 
> 
> | For example, if I have multiple topics that each appear in the
> | english version of my home page, each occurence in every topic
> | shares the same identifier, and are reified by one topic whose
> | subjectIndicatorRef is that single occurence identifier.
> 
> Here it seems that you are making a common mistake: the resource
> referred to by this occurrence is *not* the same as the occurrence.
> The resource is just the resource, while the occurrence represents the
> relationship between the resource and the topic.


In the example of 3.9.1 of xtm 1.0 (<occurence> Element)

<topic id="hamlet">
. . .
	<occurrence id="hamlet-in-xml">
		<instanceOf> ...</instanceOf>
		<resourceRef xlink= ". . .>
	</occurrence>
</topic>

and the occurrence is reified by 

<topic id="hamlet-in-xml-topic">
	<subjectIdentity>
		<subjectIndicatorRef xlink:href="#hamlet-in-xml">
	</subjectIdentity>
. . .

If I create topic2 with the same occurrence as topic hamlet, are the
occurrence id's the same in both topics, or does topic2 have a unique
occurence id and the reified occurrence have multiple subjectIndicatorRefs?

<topic id="topic2">
. . .
	<occurrence id="hamlet-in-xml">
	[same elements as above] . . .
</topic>

or

<topic id="topic2">
. . .
	<occurrence id="topic2-in-xml">
	[same elements as above] . . .
</topic>

<topic id="hamlet-in-xml-topic">
	<subjectIdentity>
		<subjectIndicatorRef xlink:href="#hamlet-in-xml">
		<subjectIndicatorRef xlink:href="#topic2-in-xml">
	</subjectIdentity>
. . .


Regards,
Howard