Re: Question about Date & Darwen <OR> operator

VC wrote:
> What is a "cylidric set" ? Probably you meant 'cylindric set algebra'
> rather than a "cylindric set". If so, it's unclear whether talking about
> databases in terms of cylindric set algebra is more insightful or clarifying
> than doing the same in terms of relations and predicates. If not, what
> exactly do you mean by "Cylindric sets are geometric objects which are
> invariant under projection" ?

I take back my reference to cylindric sets.

Let me give a very succinct lattice definition instead.

A <OR> B == (A /\ 11) \/ (B /\ 11) \/ (A /\ B /\ 00)

where
\/ is (generalized) union
and
/\ is join Received on Wed Sep 07 2005 - 22:46:34 CEST