everyone. I have a question about an irreducible representation of the (full) group $C^*$-algebra of an infinite dihedral group $D_\infty$, denoted by $C^*(D_\infty)$ Ultimately, I'm interested in finding a primitive ideal space of $C^*(D_\infty)$ which is the kernel of irreducible representation of $C^*(D_\infty)$. But I'm having a hard time finding it. $C^*(D_\infty)$ is isomorphic to $A$, the universal $C^*$-algebra generated by two projections, $p,q$. So say $\pi$ is a representation of $A$ on some Hilbert space, $H$. Then $\pi(p)$ and $\pi(q)$ are projections on $H$. So using this fact, should I consider an irreducible representation on $A$ first? Or should I find pure states on $C^*(D_\infty)$ first since they correspond to irreducible representations of $C^*(D_\infty)$? I'm fairly new to this stuff, so any reference will be definitely appreciated And thank you in advance.