Re: So let me get this right:

Oops! "DBMS_Plumber" <paul_geoffrey_brown_at_yahoo.com> was seen spray-painting on a wall:
> David Cressey Said:
>> I don't quite agree. Here's an excerpt from the on-line copy of [1]:
>
>
> Well, I agree with everything you've just said (except for what I think
> your definition of "complex domains" is).
>
> I would clarify matters by asserting that a system possesses RVAs when
> relational operators can be applied to values in a relation's
> attributes. I *think* Codd's term "nonsimple domains" refers to
> precisely this kind of situation. For example, complex numbers are a
> fine domain in mathematical logic, and are 'non-simple' in the sense of
> being 'non-atomic'. Complex numbers--as well as rational numbers,
> vectors, and matrices, etc--are not excluded so long as their contents
> cannot be accessed using project/restrict/join etc. Just data in
> relations, thank you very much.
>
> For 'non-simple' domains where the contents of the domain *can* be
> accessed with project/restrict/join, Codd introduces "normalization".
>
> (Confession: I have not read D&D's latest thoughts on RVAs, so I might
> be mis-characterizing their position.)

What is there about complex numbers that make them "non-atomic"?

The fact that they consist of two portions, whether that be:

1. The real versus imaginary portions, or
2. Angle versus distance does not seem to me to make them any less "atomic" than would be the two portions of a rational number.

After all, a rational number consist of two portions, in much the same way:

1. Numerator and denominator, or
2. Integer portion and fractional portion.

I see no reason for complex numbers to be considered any less "atomic" than rational numbers.

They're certainly treated as first class data types in a number of computer languages...

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