eja/TODO

   1 1. Add references and start citing them.
   2
   3 2. Profile (and fix?) any remaining slow operations.
   4
   5 3. When we take a Cartesian product involving a trivial algebra, we
   6    could easily cache the identity and charpoly coefficients using
   7    the nontrivial factor. On the other hand, it's nice that we can
   8    test out some alternate code paths...