Re: Proposal: 6NF

From: Brian Selzer <brian_at_selzer-software.com>
Date: Wed, 04 Oct 2006 13:22:03 GMT
Message-ID: <%zOUg.8386$GR.2556@newssvr29.news.prodigy.net>

"JOG" <jog_at_cs.nott.ac.uk> wrote in message news:1159954091.119164.155490_at_m73g2000cwd.googlegroups.com...
> All of your points represent a wild goose chase in my eyes Brian. A
> proposition with a NULL in it is no proposition at all. From a logical
> perspective, case closed. A relation tuple with a NULL in it is no
> relation tuple at all. From a mathematical perspective, case closed.
> Trying to invoke the 'kludge perspective' is hardly going to convince a
> theoretical newsgroup.
>

Is the empty set a value? Yes, it is. So why can't a null be?

By your reasoning, a proposition with an integer in it is no proposition at all; a proposition with a string in it is no proposition at all; a proposition with a widgit in it is no proposition at all.

Also, haven't you heard of the existential quantifier? For example, if a schema {X, Y, Z} has X as a key and Z can be null, then the sentence

EXISTS x (P(x) XOR Q(x))

where P is defined in terms of X and Y and where Q is defined in terms of X, Y, and Z is a perfectly valid construct in FOPL. Received on Wed Oct 04 2006 - 08:22:03 CDT