Re: MV Keys

From: x <x_at_not-exists.org>
Date: Tue, 7 Mar 2006 10:46:25 +0200
Message-ID: <dujh93$fq5$1@emma.aioe.org>

"Marshall Spight" <marshall.spight_at_gmail.com> wrote in message news:1141720100.794765.5770_at_e56g2000cwe.googlegroups.com...
> Jon Heggland wrote:
> > marshall.spight_at_gmail.com says...
> > >
> > > But isn't a tuple a subtype of a relation?

> > Not according to the definitions I prefer. I feel uncomfortable with the
> > circularity this would entail: That a relation is a set of relations(?).

> Relation: a subset of a product of sets
> Tuple: a subset of cardinality 1 of a product of sets.

> Seems like a subtype to me. Every place a relation value
> could be used, a tuple value could be used instead.

> Note there is no circularity required.

How do you know when you look at a set or at an element ? ;-) Received on Tue Mar 07 2006 - 02:46:25 CST