Re: Notions of Type

From: Aloha Kakuikanu <aloha.kakuikanu_at_yahoo.com>
Date: 17 Aug 2006 17:11:17 -0700
Message-ID: <1155859877.882289.300510@i42g2000cwa.googlegroups.com>

paul c wrote:
> Aloha Kakuikanu wrote:
> > Keith H Duggar wrote:
> >> Marshall wrote:
> >>> Very true. Of the various relational operators that have
> >>> been identified over the years, only a few, like union,
> >>> are really algebraic.
> >
> > Except that union applies to relations of the same arity only.
>
> I thought that was only a practical restriction, ie., in theory, any
> relations can be unioned?

Which theory:-?

In classic RA they aren't.

In D&D algebra they are. In relational lattice they are too. Received on Thu Aug 17 2006 - 19:11:17 CDT