Re: object algebra

"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c1nole$od2$1_at_news.netins.net...
> "Marshall Spight" <mspight_at_dnai.com> wrote in message
> news:%uz%b.414746$xy6.2350159_at_attbi_s02...
> >
> > I am against nulls. I'm not sure, but I think perhaps the only
> relationship
> > I recognize is set membership. I do not currently see the need for
> different
> > kinds of relationships.
>
> There is something easy about this approach and I'll admit I haven't caught
> up with all postings in this thread, but I toss this out. It seems to me
> that if we have three propositions:
>
> John is a 30 year old Calvinist who has pledged $30,000
> Sara is a 20 year old Methodist who has pledged $10,000
> Dora is 40 years old and has pledged $20,000
>
> then it makes sense to be able to store and retrieve these. Having a value
> (yes, a value) for an element that effectively means "this proposition does
> not include information of this type" makes sense. I agree there should not
> be a NULL that is the absense of a value. A two-valued logic yields fewer
> s/w bugs, for one thing.

Right.

If the predicate is:

X is a Y-year-old member of sect S who has pledged Z dollars

then it's pretty easy to see how we might consider

S = {Calvinist, Methodist, Baptist, Unknown}

A lot of things are simpler and easier this way.

Marshall Received on Sat Feb 28 2004 - 05:47:34 CET