Re: Relational Lattice, what is it good for?

vc wrote:
> Mikito Harakiri wrote:
> [...]
> > Working out the left side of distributivity equation we have:
> >
> > A && (B || C) = { (x,v,t) | A(x,t) and ( exists y B(y,v,t) or exists z
> > C(z,v,t) ) }
>
> With the relations B and C both being empty, you'd get an emtpy set
> regardless of A.

Yes.

> WIth either B or C (or both) being non-empty, you'd
> get {(x, v, t) | A(x,t) }

Why? The v variable (as well as t) is binded with the "exists y B(y,v,t) or exists z
C(z,v,t)" expression.

> where it's unclear what domain 'v' ranges
> over. Is that what you've intended ?

I don't see domain dependence there. Can you be more specific? Received on Sun Feb 19 2006 - 12:07:32 CST