terminological obscurity

[Heather Coppersmith]

On Tue, 01 Jun 2004 23:11:21 GMT,
Arthur <ajsiegel at optonline.com> wrote:

> On Wed, 02 Jun 2004 00:38:28 +0200, "Martin v. Löwis"
> <martin at v.loewis.de> wrote:

>>> And the above sentences implies, and I could independently
>>> imagine, a list might cohere around nothing more then the
>>> concept of existence.

>> Correct. Of course, people typically collect things in a
>> collection to have algorithms operate on the elements of a
>> collection, so a collection of all things that exist would not
>> be useful, and would be difficult to create.

> Well I don't intend to be being quite *that* abstract.

> In fact I worked a bit today not far from this domain, at least
> in my interpretation of it.

> An export routine for a 3d scene. A list is created dynaimcally
> of anything in the scene that exists, as it is created - lights,
> cameras, geometric objects, textures, include file directions,
> overrides of defaults,etc, and etc.  (I am exaggerating slightly
> to make my point, but little)

> A 3d scene is often conceived as a World, The list in some sense
> saves state, and about the only qualification for inclusion in
> the list is existence.

> The list is iterated, and enough about the element determined to
> be able to introspect the essential data needed to create
> relevant information in a form that can be parsed by an
> unrelated application, to therby have the World recreated by
> that other application.

> Even on the output side, since the information needed is
> determined by another application, and varies by the identity of
> the element - little "homogeneity" is found.

My criterion for homogeneity is "what happens if I shuffle these
elements?"  By this criterion, that list of elements in the World
*is* homogeneous, regardless of the types or the contents of the
data (unless the defaults and/or overrides are somehow cumulative
or implicitly ordered).

OTOH, an individual element's spatial coordinates (be they X, Y,
Z; rho, phi, theta; or something else) are heterogeneous because
if I shuffle them, then the object shows up in a different place
(certain degenerate symmetry cases notably excepted).

Regards,
Heather

-- 
Heather Coppersmith
That's not right; that's not even wrong. -- Wolfgang Pauli