Re: Proposal: 6NF

Brian Selzer wrote:
> >> Is the empty set a value? Yes, it is. So why can't a null be?
> >
> > Because an empty set is a value and a NULL is not.
> >
>
> Why not?

> The empty set /indicates/ the absence of a value, yet it /is/ a value; a
> null /indicates/ the absence of a value, yet it /isn't/ a value? Why the
> double standard?

The *absence of value* (known as missing data) certainly is not a value . A value is the output of a function. As a missing data is several possible outputs there it is NOT a value but several possible value. The *unpredictability* of a missing data disqualifies it as a value.

The empty set OTOH perfectly qualifies as a value as it is the output of a function that can be defined and predicted. Received on Fri Oct 06 2006 - 08:07:17 CDT