Re: dependency function, horn function, BCNF normal form
From: Jan Hidders <hidders_at_uia.ua.ac.be>
Date: Sun, 17 Feb 2002 11:08:52 +0100
Message-ID: <3c6f8200$1_at_news.uia.ac.be>
Date: Sun, 17 Feb 2002 11:08:52 +0100
Message-ID: <3c6f8200$1_at_news.uia.ac.be>
"Ashish Mittal" <mittalashish_at_yahoo.com> wrote in message
news:RYHb8.70322$fK1.4190063_at_rwcrnsc54...
> If I have
>
> PF~A and AF~X then
>
> I get PF~A + AF~X +PFAX
>
> which gives me
>
> PF~A+AF~X+PFAX+PF~X+PFX+PAF
>
> or PF + AF~X - How can restore the original relations from this
information?
What original relation? The relation you started with is PFAX, simply the union of all attributes. The relations you end up with are AFX (the split off funct. dep.) and PFA (what remains after the split of the original relation).
- Jan Hidders