[sc34wg3] RM4TM SLUO : Objective or Requirement?

[Sam Hunting]

On Fri, 22 Nov 2002, Bernard Vatant wrote:

> Some thoughts about SLUO ...
> 
> In the introduction:
> 
> "Many of the key advantages of the Topic Maps paradigm derive from the achievement of its
> primary objective, the "Subject Location Uniqueness Objective", which is to make
> everything known about every subject in a topic space accessible from a single location
> within that space."
> 
> And further on:
> 
> 3.4.1   One subject for each node
> 
> "In topic map graphs, only nodes can represent subjects, and every node represents a
> single subject." [1]
> 
> Question en paasant : Why not use the word "topic" instead of "node" throughout? To what
> extent is the above different of all the existing prose in ISO 13250, XTM 1.0, Published
> Subjects TC ... "In a topic map, a topic is the formal representation of a single
> subject". The notion of having nodes in the TMG representing "implicit" subjects that are
> not topics in the corresponding topic map is IMO extremely confusing and hard to grasp.
> 
> Now a core issue ...
> 
> If I understand well the SLUO, out of RM prose and recent Steve Newcomb's comments,
> SLUO is not expressed by 3.4.1 but by the reverse:
> 
> "In a topic map graph, every subject is represented by a single node" [2]
> 
> That I can't find anywhere explicitly expressed in the document - did I miss it?
> I assume 3.4.1. means what it says. If it is intended to express also the SLUO, it's a bug
> to be fixed.
> 
> OTOH if SLUO is only an Objective, it should be expressed by:
> 
> Recommendation:

REF: parid0034
TXT: In a topic map graph, every subject is represented by a single node
FIX: In a topic map graph, every subject *should be* (as far as
possible) represented by single node
COM:  There is *no way* to make sure that two distinct
> topics (nodes) do not *represent in fact the same subject* because of the above remark.
> Subjects that are considered implicitly distinct in a given topic map, on the basis that
> they are represented by distinct topics with distinct SIDPs, might be considered identical
> by another topic map on the basis of new discovered properties ... This is a frequent
> process in progress of knowledge that subjects considered as distinct at some point are
> discovered as being the same later on. Think about various historical apparitions of
> Halley's comet before Halley's discovery that they were the same one returning ...

END

> So the RM has to ensure that merging does not split existing subjects, but it has to allow
> merging of subjects considered previously as distinct, and admit that in many cases, the
> same subject will be represented by different nodes, because the identity of subject for
> those nodes has not yet been discovered ... In that spirit, SLUO should be considered only
> as a pragmatic guideline, and not an absolute Requirement.
> 
> This would lead hopefully to relax a certain number of convoluted constraints discussed
> lately.
> 
> Bernard
> 
> -------------------------------------------------------------------
> Bernard Vatant
> Consultant - Mondeca
> www.mondeca.com
> Chair - OASIS TM PubSubj Technical Committee
> www.oasis-open.org/committees/tm-pubsubj/
> -------------------------------------------------------------------
> 
> 
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> 

Sam Hunting
eTopicality, Inc.

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