Re: Objects and Relations

> > > > > > what is a relational expression for the string bob?
> > > > > { (0, 'b'), (1, 'o'), (2, 'b') }
> > > > Is the following relationally equivalent?
> > > > { (2, 'b'), ('b', 0'), ('o', 1) }
>
> > > No. The parenthesized elements within the braces can be reordered;
> > > the elements of the ordered tuple within the parentheses cannot.
>
> > What is the logic/proof/rationale that allows one
> > to go from sets with unordered elements to sets with ordered element?
>
> We do not create a new kind of set.
> Rather, we use one set to model the order of another set.

I still can't understand the logic/rationale explaining the transition from sets with unordered elements to sets with ordered elements, either from above or Chapter 7 of Schuam's Outline.

If unordered sets are the foundation, how can one express the string 'bob' with unordered sets only? Received on Wed Jan 31 2007 - 04:41:55 CET