Re: Relational Lattice, what is it good for?

From: Marshall Spight <marshall.spight_at_gmail.com>
Date: 17 Feb 2006 21:36:10 -0800
Message-ID: <1140240970.213820.51040_at_o13g2000cwo.googlegroups.com>

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.

Marshall Received on Sat Feb 18 2006 - 06:36:10 CET