clarify axioms using `causally up\downstream`

[markus-rothkoetter]

Description of the issue

This issue is a follow-up of #1137 with the following elements originating from comment 💬:

Element 1:

The def of causally downstream or within is Inverse of causally upstream of or within. Really, RO-developers? Add maybe an editor note with an outspelled def?

Element 2:

It costs me some brain gym to follow the axioms but it seems to hold. We should also add the inverse axioms, else this will cause confusion, e.g. 'ocean current' 'causally upstream or within' some 'marine current energy transformation'.

Element 3:

The other point I'm stumbling on: when does the ocean current process end? See: P 'causally upstream or within' q iff (1) the end of p is before the end of q and (2) the execution of p exerts some causal influence over the outputs of q; i.e. if p was abolished or the outputs of p were to be modified, this would necessarily affect q.

Ideas of solution

• Element 1:
  Do we need a custom annotation? It'd be beneficial from my perspective.
  Have there been any similar cases in the past? @stap-m
• Element 2:
  still think about the overall effects of this
• Element 3:
  @stap-m , have you been thinking about the definition of ocean current-process itself aka "is there an end at all?" or did you had a different aspect in mind?

[stap-m]

This is not that urgent, so I'll move it to the next Milestone.

[l-emele]

@stap-m : This issue is now open for 1½ years without any progress? Is there still any wish to solve this issue? Else we should close it or move it at least to the newly created meta milestone.