Re: 4NF is Where It Is At! [WAS Re: 1:1 relationships]

Hmm...

how about the following situation, as defined by the (hypothetical) phone company:

"You can take your phone number with you when you move, if and only if your new address is served by the same CO (Central Office?) as the old address was served by.

If, however, your new address is served by a different CO, then you may not take your phone number with you."

Now what are the implications for dependency, and the corresponding implications for normalization?

--
Regards,
    David Cressey
    www.dcressey.com