Let R = Z7[x]. Show that R is not isomorphic to Z.
The Attempt at a Solution
One of the necessary conditions for an isomorphism f is that f be one to one. So consider 8x in Z. f(8x) = x, f(1x) = x. So f cannot be an isomorphism. I'm clearly missing...
Are you on a windows/mac/linux machine? In general, you are still best off using SLIME. You don't need to worry about it being unmaintained - it actually gets updated very frequently...the same can be said of Emacs.
On the other hand, you might consider learning Clojure. Common Lisp is really...