Editing Natural transformation (section)

===Double dual of a vector space===
For example, if <math>K</math> is a [[field (mathematics)|field]], then for every [[vector space]] <math>V</math> over <math>K</math> we have a "natural" [[injective]] [[linear map]] <math>V \to V^{**}</math> from the vector space into its [[double dual]]. These maps are "natural" in the following sense: the double dual operation is a functor, and the maps are the components of a natural transformation from the identity functor to the double dual functor.