Re: Conjoinment

[Mark-Jason Dominus <mjd@xxxxxxxxxx>]

> >That's what I was thinking.  Any time someone is going to want to have
> >a relationship that is one-to-many, they will need to do this.
> 
> Well noted.  The question of whether each new dimension
>  will need its own new conjoined mate is less clear to me.

Each one might not, but I think that many of them will.  d.contents
and d.inside express hierarchy.  I think whenever the user wants to
express another hierarchical relation, they will need to create a new
pair of dimensions that are related in the same way that
contents-inside are.  Re-using d.inside and d.contents will not always
work for this.

For example, let's consider a representation of the systems of the
human body.  (Fig. 1; GIF version attached.)


        Body -- Digestive --   Stomach
                    |             |                   +---> d.???
                    |          Esophagus              |
                    |             |                   V d.???
                    |          Sm. Intestine
                    |             |
                    |          Lg. Intestine 
                    |
                Nervous   --   Brain        --  Cerebrum
                    |             |                |
                    |          Spinal Cord      Cerebellum
                    |             |                |
                    |          Periphery        Limbic System
                    |             |
                    |          Optic Nerve
                    |
                Circulatory -- Heart
                    |            |
                    |          Femoral Artery
                    |
                 Endocrine  -- Adrenal
                                  |
                               Prostate
                                  |
                               Liver



This example has weaknesses, but my main point is that hierarchies
exist and that any hierarchy will serve as an example here.

This shows the same sort of structure that a contents-inside structure
has.  For example, the small intestine is part of the digestive
system.  What are the X and Y dimensions?

I can think of three ways to go here:

1. Use X=d.inside      Y=d.contents.

2. Use X=something new Y=d.contents.

3. Use new dimensions for both X and Y.

1 is no good, becayse it might be inappropriate to use d.inside as the
X dimension here:

	Digestive -- Stomach -- Ham Sandwich         +---> d.contents

Oops; this is wrong because the sandwich is not part of the digestive system.

Here's what's wrong with plan #2.  The  Y direction in figure 1 is
d.contents, although the x.direction is something like
d.bodysystemincludes rather than d.contents.

Consider what happens if you say that the heart is inside the chest.
Here's another view of the same space: (Fig. 2)

	Chest -- Heart                   +---> d.inside
                   |                     |
                 Femoral Artery          V d.contents


The (heart-femoral artery) link was present in the previous picture,
so it has to be here too.  You've just said that the femoral artery is
inside the chest, which is wrong; it's in the leg.  So plan #2 is no good.

I think the only thing that works is to say that in figure 1, X is
d.bodysystemincludes and Y is d.bodysystemcontents or some such.  






mjd@xxxxxxxxx                                             Mark-Jason Dominus
mjd@xxxxxxxxxx                              Plover Systems, Philadelphia, PA