## Re: [xsl] Can sets have order?

 Subject: Re: [xsl] Can sets have order? From: Uche Ogbuji Date: Thu, 25 Jan 2001 09:53:03 -0700
```> > This is not true.  If youopen almost any discrete math book,
> ah but what about books on set theory...
>
> > Are you seriously tellimg me that those sets are not ordered?
> yes.
> The underlying set is unordered.

I think this identifies this entire discussion as a quiddity.  I'm not
interested in playing that game.  If I were, I could also go about saying

"Grass does not have a color.  The underlying grass is uncolored."

"Bricks do not have a weight.  The underlying brick is weightless."

These are true according to some construction, but not very useful in many
contexts.

There is no reason why what you consider an extrinsic property of sets, an
ordering, cannot also be considered an intrinsic property, especially if the
latter is more useful.

In the current discussion we are discussing node sets.  Since node sets have
an order, and node sets are invalid without an order, they are an ordered set.

Not that far off the wall, really.

> > Can you cite anything in the spec that indicates that the order is not
> > intrinsic?
>
> Mainly of course we are just arguing about words, for the fun of it,
> but if one was constructing ordered sets I would expect ancestor::*
> to construct the set of ancestors with reverse document ordering,

Why?

> It just constructs the set of ancestors.

In a particular order, right?  Do you claim that it can return a node set in
any order besides reverse document order?

So why is this not an intrinsic property?  Besides any quibbling.

> your model, but that's an implementation detail, I've been a pure
^^^^^^^^^^^^^^^^

> mathematician too long to worry about implementation details:-)
^^^^^^^^^^^^^^^^^^^^^^

That explains a few things.  I bet you also think that Lisp does not have
lambda functions.

--
Uche Ogbuji                               Principal Consultant
uche.ogbuji@xxxxxxxxxxxxxxx               +1 303 583 9900 x 101
Fourthought, Inc.                         http://Fourthought.com
4735 East Walnut St, Ste. C, Boulder, CO 80301-2537, USA
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