Description: Define the class of all left vector spaces. A left vector space over a
division ring is an Abelian group (vectors) together with a division ring
(scalars) and a left scalar product connecting them. Some authors call
this a "left module over a division ring", reserving "vector space" for
those where the division ring is commutative, i.e., is a field.
(Contributed by NM, 11-Nov-2013)