Direct product of groups: Let (G, ∗G) and (H,
∗H) be groups, with identity elements eG and
eH, respectively. Let g be any element of G, and h any
element of H. (a) Show that the set G × H has a natural group
structure under the operation (∗G, ∗H). What
is the identity element of G × H with this structure? What is the
inverse of the element (g, h) ∈ G × H? (b) Show that the map...