How do you find the normal subgroups of DN?
How do you find the normal subgroups of DN? In Dn, every subgroup of 〈r〉 is a normal subgroup of Dn; these are the subgroups 〈rd〉 for d | n and have index 2d. This describes all proper normal subgroups of Dn when n is odd, and the only additional proper normal subgroups when n […]