SUO: Re: W3C approves RDF and OWL as recommendations
Adam,
When things are related, it is important to show
the relationships independently of the particular
syntax as a relation or as a role.
AP> Could you elaborate on why separating roles
> and relations is a bad thing? To be sure,
> if two notions can be combined, then that does
> indeed improve sharing and reduce complexity,
> but only if that is not at the expense of
> creating an incorrect formalization.
You certainly don't want to say something that
is incorrect. But in English you can talk about
the set of parents who attend the PTA meetings
without creating any confusion with the notion
of parent as a relation. What problem are you
trying to solve or avoid?
AP> Parent is a transient role and thus has not
> been formalized as a class in SUMO. If 'parent'
> were made a class 'Parent', then an individual's
> class membership could change over time, which
> is a problem.
Why? People don't get confused about the idea
when stated in English. Why should they get
confused when it is stated in logic? Why should
you change the syntax depending on how long the
relationship lasts?
AP> This is often the case for relations.
> It would make no sense for example, for the
> 'patient' role also to be a class, for the
> same reason.
Why not? A medical information system should
certainly be able to represent the sets of
patients, nurses, or doctors at any particular
point in time. Those sets are constantly
changing. So what?
AP> There are pragmatic boundary cases to this
> issue, but the general approach to representing
> transient characteristics in relations is fairly
> standard and sound.
By what standards? There's no contradiction in
the way people talk about these matters in English.
It would be just as sound and logical in logic.
John