# Re: Proposal: 6NF

Date: Fri, 13 Oct 2006 00:26:31 +0200

Message-ID: <tvfti25ovbi5b7nv2k2feqk7adcl3mjmv3_at_4ax.com>

On Wed, 11 Oct 2006 15:33:01 GMT, Brian Selzer wrote:

(snip)

*>>>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?
**>>
**>> Wrong. The empty set *IS* a value. It's domain is the domain of sets. A
**>> set is a value that can hold zero, one or more values of a specified
**>> domain. The empty set happens to hold a zero number of values.
**>
*

>Hi, Hugo.

*>
**>I believe I said that the empty set *IS* a value. It's abstract, but it is
**>a value.
*

Hi Brian,

Indeed, you did. I should have made myself clearer.

You say that, I quote, "The empty set /indicates/ the absence of a value, yet it /is/ a value". I agree that it is a value. I disagree that it indicates the absence of a value. The empty set indicates the *presence* of a value - to wit, the value {} (which, in the domain of sets, is a perfectly legal value).

(snip)

>Ø is a symbol that says, "no value here."

If Ø is your representation of the empty set (which I usually represent as {}, two accolades with nothing in between), then this is not true. {} or Ø is a symbol that represents a value, drawn on the domain of sets. This particular value from the domain of sets happpens to have zero members in the set. It is still a set (same as 0 is still a number).

Best, Hugo Received on Fri Oct 13 2006 - 00:26:31 CEST