-5. Override random_instance(), one(), et cetera in DirectSumEJA.
-
-6. Switch to QQ in *all* algebras for _charpoly_coefficients().
- This only works when we know that the basis can be rationalized...
- which is the case at least for the concrete EJAs we provide,
- but not in general.
-
-7. Pass already_echelonized (default: False) and echelon_basis
- (default: None) into the subalgebra constructor. The value of
- already_echelonized can be passed to V.span_of_basis() to save
- some time, and usinf e.g. FreeModule_submodule_with_basis_field
- we may somehow be able to pass the echelon basis straight in to
- save time.
-
- This may require supporting "basis" as a list of basis vectors
- (as opposed to superalgebra elements) in the subalgebra constructor.
-
-8. Implement random_instance() for general algebras as random_eja().
- Copy/paste the "general" construction into the other classes that
- can use it. The general construction can be something like "call
- random_instance() on something that inherits me and return the
- result."
-
-9. Use charpoly for inverse stuff if it's cached.
+5. In CartesianProductEJA we already know the multiplication table and
+ inner product matrix. Refactor things until it's no longer
+ necessary to duplicate that work.