[topicmapmail] DM zero source locators

[Murray Altheim]

Lars Marius Garshol wrote:
> * Kal Ahmed
> | 
> | Topics are different - they have multiple identities: the source
> | locator, the subject indicator and the subject address. AFAIK the
> | practice when using subjectIndicatorRef in instanceOf is to call
> | into existence a topic which has the specified URI as a subject
> | indicator, but not necessarily any source locator. Because you *can*
> | identify topics through their subject indicators, this is not really
> | a problem (e.g. in tolog you can use a subject indicator as a query
> | parameter).
> | 
> | Other information items are different - if an occurrence information
> | item has no source locator, it cannot be addressed. To my mind, the
> | question is whether the DM should *require* a source locator for all
> | information items. My feeling is that being permissive is a good
> | thing in this case - if your system requires an item to be
> | addressable, give it a source locator, but I would be wary about
> | requiring TM processors to augment the DM with source locators, not
> | least because such locators are not required by XTM syntax.
> 
> Amen. There isn't really that much more to say about this, I think.

Yes, I agree as well. If an author needs such a thing in order to
make a statement, great. But requiring it puts a heavy burden on
processors. In my early experiments with Cyc and the ITIS zoological
taxnomy (where I had animalia with several hundred thousand topics),
something like this could make the difference between reasonable and
unreasonable from a processing perspective. And if it's only necessary
in a few places, that'd be a big waste of resources.

Murray

...........................................................................
Murray Altheim                         http://kmi.open.ac.uk/people/murray/
Knowledge Media Institute
The Open University, Milton Keynes, Bucks, MK7 6AA, UK                    .

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