Re: Issues with the logical consistency of The Third Manifesto

I'm nowhere near as deep into theory as the three of you are. But I do know a thing or two.

I think that the issues surrounding 1GB are a great deal less profound than everyone makes them out to be.

When we start to talk about "operators on a domain", we should start with the most basic operator of them all: the equality tester. The operator that is represented in SQL predicates by a single equal sign. (A single equal sign is also used by SQL to represent assignment, but that's another topic). Now when you are given "A = B" and you must return TRUE or FALSE, the question is, how?

The first step is to determine whether you are going to compare the values, or whether you are going to compare some kind of representation of the values. Now the theoreticians in this newsgroup will all shout out, in chorus: "THE VALUES!" Ay, there's the rub!

All we have inside of computers is representations. That's all there is in there, fellas. There is not a single "value" actually inside the machine. I don't care whether you follow Codd or Date or Dawn or Neo, it's all representation. I don't care whether you follow Babbage or Ada Lovelace or John Von Neumann or Knuth, it's all representation.

So the point is that, if two representations represent the same value, we have to work things out so that the equality tester can detect that fact, and return the right result. If we indeed find that two distinct representations of the "state of a relvar" can represent the same relation, then we are going to have to find an algorithm for reducing equivalent representations to a common representation, one that can be used for comparison.

You might as well call that "normalizing the relation". And there we are, back to normalizing. This DOESN'T prove that Date is wrong with 1GB. Date could be right. It may be that there is some OTHER way of normalizing a relation that isn't the same way that Codd proposed. But until you NORMALIZE the representations of relations, you can't tell whether two of them are equal. Received on Sun Nov 14 2004 - 14:16:13 CET