Recall that in a commutative ring 〈R, 0, 1, +,×〉, • 〈R, 0,+〉 is an abelian group, • 〈R− {0}, 1,×〉 is an abelian semigroup, and • multiplication distributes over addition. The same structure is a field if, in the second clause, 〈R − {0}, 1,×〉, is a group; in other words, every nonzero element has an inverse. A vector space V over a field F is an abelian group 〈V, 0, +〉 with an operation of “scal...