1 | | It inherits `_add_` and `_sub_` methods that make no sense in the coercion system. |
| 1 | It inherits `_add_` and `_sub_` methods that make no sense in the coercion system. These methods are guaranteed by the coercion system to get elements of the parent, and are supposed to give elements as well. |
| 2 | |
| 3 | Also other operations inherited from the module are problematic because they are not type-stable. The result of operations is supposed to depend only on the parents of the operands, but: |
| 4 | {{{ |
| 5 | sage: 2 * a |
| 6 | Type-(1,1) tensor on the Rank-2 free module M over the Integer Ring |
| 7 | sage: -a |
| 8 | Automorphism of the Rank-2 free module M over the Integer Ring |
| 9 | sage: (-1)*a |
| 10 | Automorphism of the Rank-2 free module M over the Integer Ring |
| 11 | sage: 0 *a |
| 12 | Automorphism of the Rank-2 free module M over the Integer Ring |
| 13 | }}} |