[
Lists Home |
Date Index |
Thread Index
]
Simon St.Laurent wrote:
>tpassin@comcast.net (Thomas B. Passin) writes:
>
>
>>Anyone have an
>>example where a new distinction, giving rise to a new
>>__classification__ term, spread rapidly?
>>
>>
>
>What exactly qualifies as a classification term?
>
>
Anything which defines a set of things i.e. a class. For example: things
which are of rdfs:type owl:Class . The term which identifies any of
these classes is it's URIref .
>I'd expect fashion ontologies, for instance, to change constantly, at
>least the ones which classify style.
>
>
I'd like to clarify a few points:
1) There is nothing that prevents ontologies from changing fairly
regularly. Ontologies themselves are just :-) documents, representations
of resources :-) that can change as often as the author desires.
Ontologies can be generated from databases etc. The only tricky point of
this is designing systems that can deal with changing ontologies, but
that is a software issue, not necessarily an ontology issue. In any case
the WebOnt WG, which has a good number of people who have lots of
experience with ontologies has considered these issues, indeed from the
"use cases and requirements" document:
http://www.w3.org/TR/webont-req/#goal-evolution . Note *requirements* R3
"explicit ontology extension" and R6 "versioning information" which are
relevent to this issue.
2) although the world is constantly changing, relationships need not so
constantly change. For example, *you* and *your father* -- I don't need
to know any details about you, nor about your father, and indeed both
you and your father are constantly changing -- even for deceased people,
for example, the "time since birth" is a property whose value is in a
constant state of change. "physical location" is another property which
might be in a constant state of change etc. etc. Nonetheless, the
*relationship* <#Simon> :sonOf _:1 between the two of you need not
change (I haven't even assigned a URI to your father!)
The point about this is that the constraints imposed by any ontology do
not (typically) result in any single state of affairs, rather a *range
of states of affairs*. A good ontology might capture a wide range of
states while at the same time imposing the proper constraints on these
states.
Admittedly time dependent changes in the state of the world remains an
area of current research for ontologies, OWL/RDF in specific, but while
OWL may not have detailed specific mechanisms for dealing with time
dependent state changes, the fact that such state changes might be
important has been factored into and considered in the design of OWL
itself i.e. future extensions to OWL might indeed directly capture time
dependencies. There is no reason that one should conclude that one has
to throw out OWL, or move beyond OWL in order to model a changing world.
Language itself is in a constant state of flux, yet Wordnet.
Jonathan
|
