ABSTRACT
From these properties it can be shown that the zero element is unique and that every x EX has a unique additive inverse -x. Furthennore, it follows that 0 · x = 0 and ( -1) · x = -x for every x EX, and that a· 0 = 0 for every a E ¢1. In this notation we have used the same symbol 0 to denote the zeros of both 4> and X. As usual, the dot symbol for the product will be dropped.
