Re: object algebra

"Marshall Spight" <mspight_at_dnai.com> wrote in message news:7S60c.747$PR3.21943_at_attbi_s03...
> "Neo" <neo55592_at_hotmail.com> wrote in message
news:4b45d3ad.0402280854.760d07b_at_posting.google.com...
> > > ...Set theory knows nothing of what Date calls the "external
predicate."
> >
> > Just because we typically don't encode "external predicates" using
> > RDM, does mean Set Theory's is not capable of it.
>
> This statement is true but not applicable. It is impossible to
> encode external predicates by definition. If they were
> encodable they wouldn't be external anymore.
>
>
> > > > Number = {5, 6, blue, peach} ???
> > >
> > > Sure. Why wouldn't they?
> >
> > Given EyeColor = {red, brown, NOT_APPLICABLE}
> > Given the table:
> > Person EyeColor
> > ------ --------------
> > Mary NOT_APPLICABLE
> > Bob NOT_APPLICABLE
> >
> > Then, Mary.EyeColor equals Bob.EyeColor leading an AI program to
> > conclude that Mary and Bob have the same EyeColor.
>
> All of Bob's eyes have the same color as all of Mary's eyes. What is
> the problem?

Since the type designer can implement the equality operation any way the designer wants, why are the colors necessarily equal? Received on Sat Feb 28 2004 - 22:03:08 CET