Re: Relational Lattice, what is it good for?

Marshall Spight wrote:
> vc wrote:
> > Marshall Spight wrote:
> > [...]
> > > So '(a, b, ab)' contains all the attributes that are only in A,
> > > all the attributes that are only in B, and all the attributes
> > > that in in both A and B.
> >
> > Assuming 'contains' means 'is the union of', '(a, b, ab)' is obviously
> > 'a union b' and 'ab' is clearly redundant. Is that what you mean ?
>
> No, not yet. Sorry I'm doing such a bad job communicating this.
>
> a is the set of all attributes that belong exclusively to A.
> b is the set of all attributes that belong exclusively to B.
> ab is the set of attributes that are common to both A and B. That is,
> it is the intersection of the attributes of A and the attributes of
> B.
>
> a, b, and ab are all distinct.
>

Oh, ok, I see what you mean now.

Thanks.
>
> Marshall
Received on Mon Feb 20 2006 - 03:37:03 CET