[sc34wg3] New SAM PSIs
Rath, Holger (empolis KL)
Thu, 13 Feb 2003 18:16:20 +0100
Murray Altheim [mailto:firstname.lastname@example.org] wrote:
> Lars Marius Garshol wrote:
> > * Murray Altheim
> > |
> > | First, I don't understand what a "subtype loop" is logically,
> > | and I can't quite think what it could be, in FOL terms. Steve?
> > A subtype loop looks as follows in LTM syntax:
> > super-sub(a : superclass, b : subclass)
> > super-sub(b : superclass, a : subclass)
> > (Assuming, of course, that 'super-sub', 'superclass', and 'subclass'
> > have been assigned the correct PSIs.)
> Okay, so this is something that is syntactically possible but
> logically impossible. I'm not sure why it's proposed, unless
> there's some domain when something's superclass can also be a
> subclass of it. I can't think of any examples.
DAML+OIL defines the equality between classes that way.