Let G = {e, a, b, c). It can be shown that a group of order 4 is
either a cyclic group of order 4 or the Klein four-group. So,
G is abelian. In this group project, without using this fact,
show that G is abelian by contradiction by answering the
following questions. Suppose that G is not abelian. Then
there exist a pair of elements that do not commute. Let us
say they are a and b.
(a) Show that ab = c.