Re: Universal Quantifier

On Jan 22, 11:02 am, "paul" <dm_ul..._at_yahoo.com> wrote:
>
> Does someone know where I can learn more about Universal Quantifier
> (Predicate logica) in relation with Database design.

Why not start here:

http://en.wikipedia.org/wiki/Universal_quantification

Always fun to spend an evening chasing Wikipedia links. At least until you end up at an article about a metal band.

Consider that database constraints can be expressed as quantified logical formula. If table A has primary key p and table B has attribute q which is a foreign key referencing A(p), we could express that as:

  forall B(q). exists A(p). p=q;

If we have a general system that lets us express constraints such as the above, we can express primary keys, foreign keys, range constraints,
and pretty much everything else, in that form.

Marshall Received on Sat Jan 27 2007 - 07:56:16 CET