            |
|         | Prod_i dA_i       | tangent vectors   |                   |
|         |                   | at a point        |                   |
o---------o-------------------o-------------------o-------------------o
| dA*     | (hom : dA -&gt; B)   | Linear functions  | (D^n)*  ~=~  D^n  |
|         |                   | on dA             |                   |
o---------o-------------------o-------------------o-------------------o
| dA^     | (dA -&gt; B)         | Boolean functions |  D^n -&g