Re: Universal Quantifier
From: paul c <toledobythesea_at_oohay.ac>
Date: Sat, 27 Jan 2007 12:09:49 GMT
Message-ID: <hiHuh.808997$1T2.253445_at_pd7urf2no>
>
>
> 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;
> ...
Date: Sat, 27 Jan 2007 12:09:49 GMT
Message-ID: <hiHuh.808997$1T2.253445_at_pd7urf2no>
Marshall wrote:
> 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;
> ...
What formula would express a primary key?
p Received on Sat Jan 27 2007 - 13:09:49 CET