Definition 1.3. A group G with binary operation is commutative, if ab=ba for any two elements a,b in G. Example 1.3, Verify that each of the groups discussed above, is commutative. Definition 1.4. Let (G,) be a group, and let HG. If H, together with the binary operation * of G, forms a group, then (H,) is a subgroup of (G,). We write (H,)(G,) to denote that (H,) is a subgroup of (G,)..
Definition 1.3. A group G with binary operation is commutative, if ab=ba for any two elements a,b in G. Example 1.3, Verify that each of the groups discussed above, is commutative. Definition 1.4. Let (G,) be a group, and let HG. If H, together with the binary operation * of G, forms a group, then (H,) is a subgroup of (G,). We write (H,)(G,) to denote that (H,) is a subgroup of (G,)..