[sc34wg3] Identification Independence?

Patrick Durusau patrick at durusau.net
Thu Nov 12 18:34:35 EST 2009


I was reading Jeffrey D. Ullman's "Principles of Database Systems" 
(1980) today, part of tracking down some references on hypergraphs.

It starts off with the usual preludes about databases and mentions:

1) physical data independence, and

2) logical data independence.

The thought occurred to me that topic maps offer a third type of 

3) entity identification independence.

After all, it is well known that two topic maps can use different 
subjectIdentifier property values for the same subject and yet, if a 
topic is added with both identifiers in one subjectIdentifier property, 
then the topics with different subjectIdentifier property values will 

That is the representative of a subject (entity in database talk) is 
independent of how the subject is identified.

Of course, entity identification can be more complex but the underlying 
principle is the same.

Don't know if that will be helpful outside of a database context but 
seems to me to be a natural extension of the "independence" theme.

Hope everyone is having a great time in Leipzig!


Patrick Durusau
patrick at durusau.net
Chair, V1 - US TAG to JTC 1/SC 34
Convener, JTC 1/SC 34/WG 3 (Topic Maps)
Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300
Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)

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