Re: Thinking about MINUS

Aloha Kakuikanu wrote:
> This was the "argument skit" reply, which I expected an "argument skit"
> followup.

No, no, no.

This is comp.databases.theory. You don't come here for an argument. This is abuse.

[snip]

> There is really little substance in this subject

Oh I dunno.

The whole point of Peano's mad rambling is that you don't need 'symbols' for each number at all. A perfectly rigorous and quite powerful arithmetic can be derived from a single anchor, and a 'relational theory relation' with enough constraints.

(Forgive me Codd, for I have SQLed).

CREATE DISTINCT TYPE Natural_Number USING 'mumble'; -- it doesn't matter.

CREATE TABLE Successor ( X Natural_Number NOT NULL PRIMARY KEY,

                                            Y Natural_Number UNIQUE
REFERENCES Successor ( X ),
                                             CHECK ( X <> Y )  );

The final axiom is really hard. So I'll just punt on it.

Note - oddly - I can't get rid of the nullability of the Y column.

Anyway, the point is that you don't need numerals at all. Cabbages or drips of ceiling wax will work just as well.

Discuss.                                             

o Received on Mon Jan 08 2007 - 14:17:43 CST