updated outermorphism doc

- use summation symbol
- removed comments at the end that are probably confusing here

doc/Outermorphism.md

@@ -7,26 +7,26 @@ Applying a linear mapping `f` to a multivector `A`:
 
 ```js
 f(A)
-= // Let A := sum{b ∈ A.baseblades} A_b b
+= // Let A := ∑{b ∈ A.baseblades} A_b b
   // Each b is a set of base vectors (technically represented as a bitmap,
   // logically a wedge product in "standard" order).
   // It is also used as an index in A to access the corresponding
   // magnitude A_b.
-f(sum{b ∈ A.baseblades} A_b b)
+f(∑{b ∈ A.baseblades} A_b b)
 = // linearity
-sum{b ∈ A.baseblades} A_b f(b)
+∑{b ∈ A.baseblades} A_b f(b)
 = // Let b := ⋀{e_i ∈ b} e_i
   // e_i is the i-th base vector in the domain
-sum{b ∈ A.baseblades} A_b f(⋀{e_i ∈ b} e_i)
+∑{b ∈ A.baseblades} A_b f(⋀{e_i ∈ b} e_i)
 = // distribute f over the wedge product
-sum{b ∈ A.baseblades} A_b ⋀{e_i ∈ b} f(e_i)
+∑{b ∈ A.baseblades} A_b ⋀{e_i ∈ b} f(e_i)
 = // Let f be given as matrix M:
-  //   f(e_i) = sum{j} M_ji E_j
+  //   f(e_i) = ∑{j} M_ji E_j
   // with
   // i: column index, j: row index
   // E_j: j-th base vector in the co-domain
-sum{b ∈ A.baseblades} A_b ⋀{e_i ∈ b} sum{j} M_ji E_j
-                           ---------------------------
+∑{b ∈ A.baseblades} A_b ⋀{e_i ∈ b} ∑{j} M_ji E_j
+                        -------------------------
 ```
 
 We implement the underlined expression
@@ -50,21 +50,3 @@ Parameters of the recursive function:
 - An accumulated "value":
   - Start with `A_b` and
   - multiply (symbolically) with `M_ji` in each recursion step.
-
-
-
-TODO It might make sense to use a class hierarchy like this:
-- `Algebra`
-  - `OrthogonalAlgebra` (~ today's class `Algebra`)
-    - `EuclideanAlgebra`
-  - `NonOrthogonalAlgebra`
-    - `ConformalAlgebra`
-
-Notes:
-- Euclidean and conformal algebra need not be separate subclasses.
-  They might just be (non-)orthogonal algebras with appropriate behavior.
-
-- A `NonOrthogonalAlgebra` manages two kinds of multivectors:
-  - "local" multivectors
-  - (wrapped) multivectors of an underlying (typically orthogonal) algebra
-  - The eigenmatrix and its inverse are used to convert between the two kinds.