Re: Proposal: 6NF

From: Jan Hidders <hidders_at_gmail.com>
Date: 12 Oct 2006 01:28:53 -0700
Message-ID: <1160641733.871211.18790_at_b28g2000cwb.googlegroups.com>


Brian Selzer wrote:
> "Hugo Kornelis" <hugo_at_perFact.REMOVETHIS.info.INVALID> wrote in message
> news:bjidi29k8crgbrh536l9t3et41chha1i1n_at_4ax.com...
> >
> > 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.
>
> I believe I said that the empty set *IS* a value. It's abstract, but it is
> a value. The set of all sets does not exist; therefore, the domain of sets
> does not exist. Consequently, the empty set does not have a domain. It has
> an abstract type, however.

Sorry for butting in, but the the empty set has lots of domains, namely all the domains in your universe that are set-valued. The assumption that there must be necessarily *a* domain for a certain value is not correct.

  • Jan Hidders
Received on Thu Oct 12 2006 - 10:28:53 CEST

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