Re: separation of church and state?

From: Marshall <marshall.spight_at_gmail.com>
Date: Sun, 07 Oct 2007 16:21:01 -0000
Message-ID: <1191774061.207930.283940@v3g2000hsg.googlegroups.com>

On Oct 7, 8:40 am, paul c <toledobythe..._at_ooyah.ac> wrote:

> Could be. Maybe one of Date's meanings is that no system that supports
> both ordering and some relational algebra is purely relational, even if
> the "pure" relational part of it could be isolated in some way from the
> rest! If so, calling the paragraph "doctrinaire" might be a bit of a slur.

In order theory, an ordered set is a pair, consisting of a set and an order relation on that set. It's not a list or anything like that. The question of data structures only comes up when (in implementation land) we want to do the computation of putting the elements in some order. What that looks like is a design decision, and I don't see any reason why it can't look like a relation, at some level at least. In other words, it could be a relation {position, element} in the case of a total order, or {position, {element}} in a preorder. (It's not obvious what it should be for a partial order.)

My sense is that Date's ideas about the solution space to this problem have been somewhat artificially constrained as a response to what SQL did.

Marshall Received on Sun Oct 07 2007 - 11:21:01 CDT