I am trying to show that a cyclic group of prime power order has only 1 composition series. Is the following correct?
Let $G=C_{p^n}$. Then as cyclic groups are abelian we have that there is a subgroup of every order dividing $p^n$, which is $1,p,p^2,…$, then these are all normal (as $G$ is abelian) and are cyclic and so are unique up to isomorphism.
So if we start of with any subnormal series $\displaystyle{\{1\}\triangleleft C_{p^i} \triangleleft C_{p^n}}$ then we can always refine it so that it is:
$\{1\}\triangleleft C_p\triangleleft C_{p^2}\triangleleft …..\triangleleft C_{p^m}$
Best Answer
That looks correct. The facts you need are: