Finding Lie Subgroups
I've been asked to locate all correct lie subgroups of $SU(2)$.
I appear to remember assuming that $U(1)$ is the only nontrivial linked lie subgroup, yet I can not fairly bear in mind just how I thought of this (do not you despise that sensation when you did something, you go on to another thing to maintain energy, and afterwards neglect what you did initially?)
Yet when it comes to the notsoconnected subgroups, I'm really stuck. I can just believe to consider the lie algebra
Many thanks for your aid -