eja: add an optimization to the TODO.

[sage.d.git] / mjo / eja / TODO

diff --git a/mjo/eja/TODO b/mjo/eja/TODO
index dd671c5fd7ab847a4c635748923bf0cba12a63ad..382fb6e67d6050dd6e8215ad2d371a5be3022057 100644 (file)
--- a/mjo/eja/TODO
+++ b/mjo/eja/TODO
@@ -1,44 +1,17 @@
-Trace inner product tests:
+1. Add CartesianProductEJA.
 
-            TESTS:
+2. Check the axioms in the constructor when check != False?
 
-            The trace inner product is commutative::
+3. Add references and start citing them.
 
-            sage: set_random_seed()
-            sage: J = random_eja()
-            sage: x = J.random_element(); y = J.random_element()
-            sage: x.trace_inner_product(y) == y.trace_inner_product(x)
-            True
+4. Implement the octonion simple EJA.
 
-            The trace inner product is bilinear::
+5. Factor out the Jordan axiom and norm tests once all of the
+   algebras pass.
 
-            sage: set_random_seed()
-            sage: J = random_eja()
-            sage: x = J.random_element()
-            sage: y = J.random_element()
-            sage: z = J.random_element()
-            sage: a = QQ.random_element();
-            sage: actual = (a*(x+z)).trace_inner_product(y)
-            sage: expected = a*x.trace_inner_product(y) + a*z.trace_inner_product(y)
-            sage: actual == expected
-            True
-            sage: actual = x.trace_inner_product(a*(y+z))
-            sage: expected = a*x.trace_inner_product(y) +  a*x.trace_inner_product(z)
-            sage: actual == expected
-            True
-
-            The trace inner product is associative::
-
-            sage: pass
-
-            The trace inner product satisfies the compatibility
-            condition in the definition of a Euclidean Jordan algebra:
-
-            sage: set_random_seed()
-            sage: J = random_eja()
-            sage: x = J.random_element()
-            sage: y = J.random_element()
-            sage: z = J.random_element()
-            sage: (x*y).trace_inner_product(z) == y.trace_inner_product(x*z)
-            True
-           
\ No newline at end of file
+6. Create Element subclasses for the matrix EJAs, and then override
+   their characteristic_polynomial() method to create a new algebra
+   over the rationals (with a non-normalized basis). We can then
+   compute the charpoly quickly by passing the natural representation
+   of the given element into the new algebra and computing its charpoly
+   there. (Relies on the theory to ensure that the charpolys are equal.)
\ No newline at end of file