Re: object algebra

"Marshall Spight" <mspight_at_dnai.com> wrote in message news:G3V%b.137291$uV3.666254_at_attbi_s51... > "Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c1nole$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.

How do we know there is only one predicate? Why do we not have two or even three predicates? Received on Sat Feb 28 2004 - 05:58:57 CET