be
a while before we get within sight of that goal, but it will help me
to name the thread after the envisioned end rather than the homely
starting place.

The basic idea here is that you have a species of graphs
and a set of transformation rules that take you from one
graph to another -- and back again, as I'm only thinking
of equational rules -- and this partitions the species of
graphs into &quot;transformational equivalence classes&quot; (TEC's).

There are many interesting excursions to be had here,
bu