Re: Can sets have order?

> >>  I'd also agree with my original statement. Terminology isn't always
> >>  consistently applied.
> >
> >Agreed here, but I can't think of a respectable terminology that restricts
> >sets to be unordered.
> >
> 
> I don't know if he's correct or not, but the eminently respectable C. 
> J. Date writes on p. 92 of the sixth edition of his well respected 
> text "Introduction to Database Systems":
> 
> "2. Tuples are unordered (top to bottom)
> 
> This property follows from the fact that the body of the relation is 
> a mathematical set; sets in mathematics are not ordered."

That (and private mail I've received) does it.  The pure mathematician (David) 
wins that point.  In pure math, sets seem strictly not to have order.

> This is a rather significant point in his discussion.

Perhaps, but rather useless in the discussion that prompted the matter.

The reason I objected to David's going on about sets not having order is that 
he seemed to be claiming that node sets do not have order.

So I'm guessing that he should rather be arguing that the WG should not have 
called node sets so (never fear, the RDF group also constantly debates whether 
the RDF M&S meant what it thought it meant when they proclaimed a model had a 
set of ststements).

Again, why would this be useful?


-- 
Uche Ogbuji                               Principal Consultant
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