Re: Proposal: 6NF

From: Marshall <marshall.spight_at_gmail.com>
Date: 8 Oct 2006 12:21:38 -0700
Message-ID: <1160335298.815821.111740@m73g2000cwd.googlegroups.com>

In my not-so-humble opinion, this whole thread is a bunch of useless talking-past-each-other. The word "null" (like all other words) means different things in different contexts, and "null" in particular means a variety of different, *incompatible* things. It seems to me that everyone is assuming it means the same thing to them as it does to the person they're talking to, at least some of the time.

[context] term

---

[math] empty set
[SQL] null
[3VL] unknown
[Java] null
[lisp] nil
[C] pointer 0
[type theory] bottom
[SML] Maybe algebraic data type
[Haskell] Maybe monad
[Nested RA] value with an empty determinant-set functional dependency
[TTM] Table Dum
[TTM] omega

... and probably many more.

Every one of these is a distinct concept, with distinct semantics. None of them can be separated from the underlying theory. It only makes sense to consider these within the context of the theory they are embedded in, and a direct comparison that doesn't take in to account how well the concept fits into its theory is leaving out important details. It is simply pointless to talk about one being better than the other without context.

What we have to do instead is consider the context, consider the desired behavior, consider the possible failure modes, and measure the semantics of any given proposal within the context of a particular theory. We can't even do that without an agreed-upon set up use cases.

I don't think we've got anything approximating consensus on what the desired behavior is.

So: what is the desired behavior? What are the use cases?

Marshall Received on Sun Oct 08 2006 - 14:21:38 CDT