Re: RE : Suggestion for SKOS FAQ

On Fri, Mar 14, 2008 at 7:32 AM, Stella Dextre Clarke <stella@lukehouse.org>
wrote:

However, SKOS may not choose to apply constraints too strictly, because:
> (a) some thesauri are carelessly constructed, and may not apply the
> standard rules very strictly, and
> (b) other types of vocabulary do not apply all the thesaurus rules, and
> SKOS wants to be flexible.


> Am I right in thinking this is the SKOS mainstream view?
>

I can't  speak for the mainstream :-)    Your chapter in Bean and Green
(2001) has been cited in support of this view, but this appears to be a
misreading.  To the extent that these statements are true, they don't imply
an intransitive semantics of 'broader':

Dextre Clarke defines a hierarchical relationships as one "assigned to a pair
of terms when the scope of one of the terms totally includes (is broader
than) the scope of the other." (Dextre Clarke 2001, p. 42)

Milstead confirms that total inclusion is the key criteria: "[The part-whole
relationship] only has to meet the test of always being true, just as with
the other hierarchical relationships."(Milstead 2001, p.60)

Example given in the SKOS Primer may be the result of subconsciously
treating  SKOS Concepts as if they were OWL Classes:

Consider for instance a case where ex2:vehicles is said to be broader than
ex2:cars, which is itself asserted to be broader than ex2:wheels. It may be
debatable to automatically infer from this that wheels is a narrower concept
to vehicles.   (Isaac and Summers 2008)

If SKOS Concepts are treated as if they defined sets of Things, then this
concern is valid.  A wheel is not a kind of vehicle.

 However, as Fischer points out, the the standards "more or less implicitly
allow that these different types of hierarchy relations may be conflated
into one hierarchical relationship in an actual thesaurus; we see this also
reflected in the title "The Hierarchical Relationship" (ISO 2788, 8.3)".
(Fischer 1998)

He explains this permissiveness with reference to the document retrieval
definition of broader-narrower given by Soergel :
"Concept A is broader than concept B whenever the following holds: in any
inclusive search for A all items dealing with B should be found. Conversely
B is narrower than A."(Soergel 1974, p. 78)

If (within the scope of the controlled vocabulary) documents about wheels
are always about cars, and documents about cars are always about vehicles,
then it must be the case that all documents about  wheels are  documents
about  vehicles, from the definition of subset.

Since SKOS was created to  model controlled vocabularies,  the broader
relationship in SKOS must be transitive.

Simon
------
Dextre Clarke, Stella G (2001). "Thesaural Relationships". In: Relationships
in the Organization of Knowledge. Ed. by Carol A Bean and Rebecca Green.
Information science and knowledge management. Dordrecht: Kluwer Academic
Publishers. Pp. 37–52.

Fischer, D.H. (1998). "From Thesauri towards Ontologies?". In: Proceedings
of the 5th ISKO Conference on Knowledge Organization. URL:
http://ipsi.fraunhofer.de/topas/publications/Fischer_1998.pdf.

Isaac, Antoine and Ed Summers (2008). SKOS Primer. W3C.

Milstead, Jessica L. (2001). "Standards for Relationships between Subject
Indexing Terms". In: Relationships in the Organization of Knowledge. Ed. by
Carol A Bean and Rebecca Green. Information science and knowledge
management. Dordrecht: Kluwer Academic Publishers. Pp. 53–66.

Soergel, Dagobert (1974). Indexing languages and thesauri: construction and
maintenance. Los Angeles: Melville Pub. Co.