[topicmapmail] Getty Art and Architecture Thesaurus On Line

[Thomas B. Passin]

[Kal Ahmed
> Is instanceOf really a transitive relation ? I don't believe it is.
>
> Kal instanceOf Homo Sapiens
>
> Homo Sapiens instanceOf Species
>
> Kal instanceOf Species ?
>
> Subclass/superclass *is* transitive, but not instanceOf. Unless you mean
> something different to a class-instance relationship by 'instanceOf'
>

I do not think that this illustrates anything about transitivity.  Rather,
this is the class/instance conundrum.  Is an "instance" of a class supposed
to be a class or an individual?  If it is supposed to be an individual, you
would not say "Homo Sapiens instanceOf Species".  If it is allowed to be a
class, how do you know how to distinguish an instance as a class form an
instance as an individual?

This has been discussed before, in this and other lists, but I confess that
I am still not clear on how to deal with the issue except to rule that an
"instance" by definition means an individual member of some class.  I gather
that this is not altogether satisfactory because sometimes one does want the
individual to be a class - although this is getting into the dangerous
waters of the class of all classes

Cheers,

Tom P