Re: Comment: ISSUE-70

On 12 Feb 2008, at 18:01, Deridder, Jody L wrote:

> Thank you, Sean.
>    I'm still, however, confused.  It seems to me that these  
> examples can
> be reasonably considered as sets and subsets.
> The set of fairy tales contains the set of Cinderella stories as  
> well as
> the set of Rumpelstiltskin stories.  The set of Cinderella stories  
> is a
> subset of the set of fairy tales.

Maybe, but think of this example:

mountain ranges

Now here, the Andes is an instance of a mountain range rather than  
being a subset. Maybe you consider that the Andes contains (errr,  
quickly consults the web...:-) Pomerape, Monte San Valentin, Alpamayo  
etc, but these are not then mountain ranges, they're mountains. So  
it's not quite subset/superset inclusion that's going on here.

> Likewise, regiments are a subset of battalions, which are in turn a
> subset of military divisions and so on.

But if we look at the later examples:

nervous system
   central nervous system

The brain is not a kind of central nervous system, e.g. the set of  
brains is not contained in the set of central nervous systems. Its a  
*part* of the central nervous system. Here we have a broader  
partitive relation.


   divisions (military)

Would you say that a regiment was a kind of army? I think probably  
not -- armies are composed of divisions, which are composed of  
battalions and so on. Again, we have a partitive relation.

What I'm trying to say here is that we shouldn't simply base our  
interpretation of broader on a subclass relationship as there are  
other ways in which it's used. SKOS is intended to be used to  
represent general Knowledge Organisation Systems, so we have a much  
"looser" interpretation of broader. If you really have a situation  
where you know you can interpret all your concepts as classes or sets  
of individuals, and you have a super/subclass relationship, then a  
more appropriate representation might be OWL [1], which then brings  
advantages such as inference and consistency checking (but also some  

Now, one could argue that the examples above lend weight to the  
argument that broader should be irreflexive. However, I think that's  
a *different* (but also important) argument.



Sean Bechhofer
School of Computer Science
University of Manchester

Received on Wednesday, 13 February 2008 09:24:12 UTC