Yes indeed. But what I'm saying is that there is actually just one nameless state machine whose coordinate system is organized as a tree who's leaves represent

Yes indeed. But what I'm saying is that there is actually just one nameless state machine whose coordinate system is organized as a tree who's leaves represent the machine's degrees-of-freedom. It's kind of an odd thing: the leaf both partitions state, and it also co-locates the DoF for changing the state (or at least it's apparent state, if you're immutable). Neat link, I'll have to check it out. I've not done erlang but I'm quite intrigued by gen_server in particular. Sorry for talking about coordinate-systems: I can't help it, I have a physics degree.