[sc34wg3] Towards TMDM 3.0

Rani Pinchuk rani.pinchuk at spaceapplications.com
Mon Feb 23 04:59:52 EST 2009

Dear Lars,

Saying that Item identifiers (or subject identifiers, or subject 
locators) were never meant to be unique *across* topic maps does not 
solve the problem really.

Section 6.2 of TMDM explains that during the merging of two
topics A and B, a new topic C is created with its item identifiers 
property set to the union of the values of A and B’s item identifiers 

Why do we do that? What is the use of collecting item identifiers from 
different topics (in possibly different topic maps) to the current one 
if they have no uniqueness outside of the topic map? How can we use 
those item identifiers?

Kind regards,


Lars Marius Garshol wrote:
  > I guess you are referring to section 4.2 of this paper? I'm afraid I
> don't see any problem in this section. Item identifiers (or subject  
> identifiers, or subject locators) were never meant to be unique  
> *across* topic maps, only *within* each topic map.
> I think if you reflect on it for a moment, you will see that in fact  
> no other policy is possible. Even your proposed change (just one [item  
> identifier], new property [item origins]) doesn't solve this. It's  
> entirely possible to create two topics in different topic maps with  
> the same item identifier. For example, in different TM engines, or on  
> different machines.
> In any case, there is no problem to be solved here. Different topics  
> in different topic maps can have the same subject identifier, which is  
> how we can have interoperability between topic maps. Item identifiers  
> are essentially the same.
> --Lars M.
> http://www.garshol.priv.no/blog/
> http://www.garshol.priv.no/tmphoto/
> _______________________________________________
> sc34wg3 mailing list
> sc34wg3 at isotopicmaps.org
> http://www.isotopicmaps.org/mailman/listinfo/sc34wg3

Rani Pinchuk
Project Manager
Space Applications Services
Leuvensesteenweg, 325
B-1932 Zaventem

Tel.: + 32 2 721 54 84
Fax.: + 32 2 721 54 44


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