Two
groups are said to be
isomorphic if there exists a
map f: G
1->G
2 such that f is a
bijection. Let G
1 be (G,+) and let G
2 be (H,*), where G and H are arbitrary non-empty sets and + and * are arbitrary operations on those sets. For g
1, g
2 in G, f(g
1 + g
2)
= f(g
1) * f(g
2) => G
1 and G
2 are
isomorphic.