[plt-scheme] Tree recursion

On Jan 22, 2008 9:29 PM, Robby Findler <robby at cs.uchicago.edu> wrote:
> You can try thinking about it algebraically. Each equality below
> corresponds to using the tree-copy just one time (well, except once
> where I took two steps at once).

I see, that makes sense. Thanks!

Is that was folks refer to as the conceptual "substitution module" of
evaluation?