Re: Columns without names

Marshall wrote:
>
> If I were just to read your last paragraph, I would say that
> the question of what is a legal column name is a merely
> syntactic question, and we are free to choose whatever
> rules we care to apply without affecting the underlying
> semantics. [...]
>
> Whoops, I'm required to go make breakfast now. Part
> 2 in a while.

Okay, the pancakes are all eaten, and I'm back.

As I said, "*If* I were just to read the last paragraph..." But elsewhere in the post, I note you said "[when] considering domain-defining statements ..."

If you're going where I think you're going, then I would propose that it is better *not* to think of domain definitions as being relations. What works better, as best I can tell, is to consider them simple sets. Then the entire issue of attribute names doesn't arise, which makes sense since for an application (domain definition) where we only ever have unary relations, attribute names is unneccessary. In fact, the relational operators on unary relations behave like (non-relational) set operators: join is like intersection, etc.

So instead of thinking of the set of natural numbers as { (0), (1), (2), ... } we think of it as { 0, 1, 2 ...} which is simpler and makes more sense. I would say that 7 is not a proposition; 7 is a value. When we put it in the context of a predicate, it gains meaning. So in the context of the predicate "The old lady across the street has X cats", the relation, (X=7) is a proposition, but 7 by itself, with no context, is a simple value.

Marshall Received on Sat Sep 16 2006 - 18:13:24 CEST