Re: Pizza Example

In article <TVoj+7HXgvfAFwwt_at_thewolery.demon.co.uk>, Anthony W. Youngman wrote:
>
> (And I'm not against maths. It's just that science is all about fuzzy
> logic, uncertainty, and statistics. But (a) my grasp of the fundamental
> theory behind that is very poor, and (b) it seems to be a lot better
> than anybody else who might be inclined to debate with me. I'm just
> looking for *scientific* proof, not mathematical, that relational theory
> works, and nobody seems willing to try to prove it.)

I'm not sure asking for "scientific" proof of something that's not a scientific theory makes sense. Newtownian mechanics offers rules by which we can describe the world. The relational model offers rules for the manipulation of propositions, whose mapping to the real world is arbitrary (but should be consistent for each individual database). I suppose I might try to put the premises of the relational model thus:

Axiomatic statements about the world form the conditions of the database. Data consists of statements which are evaluated as logical propositions against the constraints.
Queries against the database consist of the application of additional constraints (axioms) to the propositions in the database, and return all logical propositions which are true in the new axiomatic system.

So statements in a relational database are guaranteed to be true to the degree that truth can be defined by the constraints expressed in the database.

As I see it, the main two lines of "attack" are the idea that all data can be represented as statements (certainly the world is fuzzy, but how better to *automatically* evaluate truth than logic?) and the expressive capabilities of the relational model as regards conditions (but here perhaps we run into Russell's Paradox).

I am neither by training nor practice a logician, so I'm not entirely sure this description is correct, but I think it's a good starting point for discussion of the issue.

-- 
Chris Hoess