-A. Make the subalgebra class work with any subalgebra (there's nothing
- special except a_regular_element() in there).
+A. Add tests for orthogonality in the Peirce decomposition.
+
+B. Add support for a symmetric positive-definite bilinear form in
+ the JordanSpinEJA.
1. Add CartesianProductEJA.
6. Can we make the minimal and characteristic polynomial tests work
for trivial algebras, too? Then we wouldn't need the "nontrivial"
argument to random_eja().
+
+7. Solve the charpoly system with A_of_x.solve_right(x_powers[r])
+ rather than dumbass Cramer's rule.