Steve Bennett wrote:
On 8/23/06, Neil Harris <neil(a)tonal.clara.co.uk>
wrote:
The problem is different senses of
'subcategory': there's [1] "the set
of objects in B are a strict subset of the set of objects in A", which
is loop-proof, and [2] 'B is a topic that is usually discussed in the
context of A'
For example:
London -[2]-> Thames Valley -[1]-> London, comes to mind
Russia -[2]-> Soviet Union -[1]-> Russia, as well.
Good explanation!
See [[WordNet]] for a serious attempt to tease
out the relationships
between concepts in detail: there are _lots_ of possible ways that one
thing can be related to another.
One major complication not to forget is that our categories are at the
*article* level, not at the *topic* or *concept* level. Often one
article = one topic, but not always: for example, [[Beamish and
Crawford]] is about both a brewery and a beer. [[Controlled Impact
Demonstration]] covers the topics of an air safety program, a type of
jet fuel, and a specific event.
If anyone has some schemas or diagrams or whatever that could attempt
to make sense of this, I'd love to see them.
Indeed they have. However, the main efforts in this direction are so
complex and abstract that they are effectively unusable for ordinary
mortals. See, for example,
http://www.w3.org/TR/owl-features/
Clearly a strict
hierarchy as the only classificational structure is inappropriate.
However, we can also do better than unstructured tagging. What's a
good compromise? How can we get the benefits of a hierarchy where it
works, and the flexibility of tagging when it doesn't?
I like [[WordNet]]'s (relatively) simple way of identifying different
classes of relationships: even things like (say)
[[located-in::Category:Places in Texas]], or
[[subset-of::Category:Places in Texas]] would still be easier to read,
write and understand than stuff like (for example)
<owl:Class rdf:ID="TexasThings">
<owl:equivalentClass>
<owl:Restriction>
<owl:onProperty rdf:resource="#locatedIn" />
<owl:someValuesFrom rdf:resource="#TexasRegion" />
</owl:Restriction>
</owl:equivalentClass>
</owl:Class>
-- Neil