41 | | And: If we have an object O in some category (say, GF(5) in the category of fields), and an object X that is obtained from O by a forgetful functor (say, Integers(5) in the category of ~~field~~s), and we have a in O and b in X, then we typically want that a+b belongs to the "richer" structure - otherwise, we would have worked in X right away. |

| 41 | And: If we have an object O in some category (say, GF(5) in the category of fields), and an object X that is obtained from O by a forgetful functor (say, Integers(5) in the category of rings), and we have a in O and b in X, then we typically want that a+b belongs to the "richer" structure - otherwise, we would have worked in X right away. |