RE : aboutness and broader

Dear all,

I agree that the examples given by Jonathan are a bit unclear, but I think the concern is genuine, and partly share it.

In library cases, having a document's subject index automatically added with the parent concepts of the ones that were chosen by the indexer would violate the indexing specificity principle.

Notice that this problem is a bit similar to the choice between making skos:broader transitive and introducing a new 'transitive version of it' to avoid messing with the original intended meaning of concepts.
If we enforce for knowledge bases the kind of rule that Alstair proposes, then it's more difficult to make the distinction between asserted subjects and inherited ones, hampering all kind of interesting options wrt to query expansions, as explored in Uni-Glamorgan's work [1] and Alistair's thesis [2].
Maybe a special type of property (in this case, different from dc:subject) would be appropriate fo allowing these subject inferences, which are otherwise very useful in a number of cases of course (e.g. classical faceted browsing). Or maybe just mention that the rule is just an indication on how to add interesting (but not mandatory) functionality to a knowledge base...

Cheers,

Antoine
[1] http://hypermedia.research.glam.ac.uk/publications/
[2] http://purl.org/net/retrieval



-------- Message d'origine--------
De: public-esw-thes-request@w3.org de la part de Leonard Will
Date: mer. 04/06/2008 12:25
À: public-esw-thes@w3.org
Objet : Re: aboutness and broader
 

On Wed, 4 Jun 2008 at 10:30:55, Jonathan Chetwynd 
<j.chetwynd@btinternet.com> wrote
>Alistair,
>
>as always with issues around logic, the reasoning isn't always 
>apparent to the outsider...
>
>I'm not clear about your use of "necessarily", please can you expand 
>briefly?
>
>ie what does "mammals have breasts" tell us about animals?
>or "carrots are orange" tell us about vegetables?
>other than some B can be D? but not necessarily?
>
>and how does that relate to "animals are motile" not telling us about 
>mammals?
>ie all mammals are motile? is necessarily? though...
>

There is a difference between defining attributes and other attributes.

"Mammals" are a type of "animals" distinguished by the characteristic 
that they produce milk to feed their young. The facts that they have fur 
and four legs are interesting, and may be included in an ontology, but 
these do not determine hierarchical relationships in a thesaurus, 
whether or not these attributes are specific to mammals.

I don't know biological taxonomy well enough to say whether being orange 
is a defining characteristic of carrots - I suspect that it is not - 
besides the problem of "vegetables" being a rather tricky category to 
define anyway . . .

Scope notes are often usefully expressed in terms of a broader concept 
and a difference that defines a sub-set of that concept, e.g.

"flower pots" are "pots" [broader concept] "for holding flowers" 
[difference]

"thermometers" are "instruments" [broader concept] "for measuring 
temperature" [difference]

The fact that flower pots may be made of clay or plastic, or that 
thermometers may be graduated in Celsius or Fahrenheit, are attributes 
but not defining attributes.

In the classic example, a valid broader relationship is

"parrots" are "birds" [broader concept] "of the order Psittaciformes" 
[difference]

whereas it is not valid to say

"parrots" are "pets" [broader concept] ... with any difference, because 
not all parrots are pets.

Leonard Will

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