of this analogically &quot;model-theoretic&quot; strategy,
just so that we will have the security of this concrete and shared experience
on which to fall back at every later point in what may quickly become a rather
abstruse discussion.  Here then is the rest of the necessary chain of equations:

o-----------------------------------------------------------o
| Equation E1.  Proof 2.  (=&lt;=)                             |
o-----------------------------------------------------------o
|                        